Repository: bitcoin/bitcoin (language: cpp)

Issue:
Implement auto-fee leveling when spending unconfirmed outputs
Right now if a user makes a low feerate payment then later makes a higher feerate payment that spends the unconfirmed output from the prior payment the wallet is just completely blind to the prior low feerate.

This can contribute to long unconfirmed chains forming when the necessary feerates go up because later payments, though paying a higher rate, don't pay enough to pull their ancestors up to their target rate.

Instead, we should probably reduce the effective value of unconfirmed outputs by the amount needed to bring them up to the target feerate, and increase fees by that much, so that when a feerate of x s/b is set, the actual effect rate delivered is actually x s/b.
 


Discussion / hints:
> the actual effect rate delivered is actually x s/b.

Makes sense. In a way it would promote CPFP right?
But how to send unconfirmed transaction? 'sendmany' with 'minconf 0' is not working.
Concept ACK.

We should not automatically pay for previous transactions from strangers. However our wallet only spends our own unconfirmed change, so there's no abuse risk here.

There is risk of confusion when the total fee is higher than a user would expect, but the total fee already varies as a result of coin selection.

In the GUI we can make it clear in the send screen, when a user selects a fee rate, that the total fee includes compensation for n parent transactions. Currently the expected confirmation time displayed in the GUI is plain wrong if there's a parent.

In the RPC we could make this new behavior clear in the documentation.
One issue is that we have a mixed bag of coin selection, BnB which uses effective value, and the legacy "loop" one which does not. In the loopy setup we'd have to just make sure that the `nFeeNeeeded` goes up by the proper fee amount IFF that unconfirmed output is selected. 
Concept ACK

The additional cost of bumping the parent should be taken into account when calculating the effective value of the unconfirmed UTXO. This would additionally dissuade selection of UTXOs with low fee rate parent transactions, especially when we start preferring coin selection results with a lower waste as proposed in https://github.com/bitcoin/bitcoin/pull/22009.

I am goint to take a stab at implementing the auto-fee leveling.
@Xekyo were you able to make some progress on this? More people are realizing this limitation and hitting this in the wild, is this still being actively worked on? Is there a more detailed discussion about this somewhere else?
Sorry for the slow progress. @glozow implemented an interface so that we can access mempool information about unconfirmed ancestor transactions and my next step is to use this information in the waste metric and coinselection functions. I aspire to have a PR by the end of the month.
Great, thanks to you both!
@t-bast, I got a branch here: https://github.com/Xekyo/bitcoin/commits/2022-06-ancestor-aware-funding, but PR is still pending

Fix patch:
diff --git a/src/bench/coin_selection.cpp b/src/bench/coin_selection.cpp
index 0e110a653af9f..249b76ee85133 100644
--- a/src/bench/coin_selection.cpp
+++ b/src/bench/coin_selection.cpp
@@ -79,7 +79,7 @@ static void CoinSelection(benchmark::Bench& bench)
     };
     auto group = wallet::GroupOutputs(wallet, available_coins, coin_selection_params, {{filter_standard}})[filter_standard];
     bench.run([&] {
-        auto result = AttemptSelection(1003 * COIN, group, coin_selection_params, /*allow_mixed_output_types=*/true);
+        auto result = AttemptSelection(wallet.chain(), 1003 * COIN, group, coin_selection_params, /*allow_mixed_output_types=*/true);
         assert(result);
         assert(result->GetSelectedValue() == 1003 * COIN);
         assert(result->GetInputSet().size() == 2);
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index dd664165d303c..b5243725ad0e7 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -216,6 +216,43 @@ class Chain
     //! Calculate mempool ancestor and descendant counts for the given transaction.
     virtual void getTransactionAncestry(const uint256& txid, size_t& ancestors, size_t& descendants, size_t* ancestorsize = nullptr, CAmount* ancestorfees = nullptr) = 0;
 
+    //! For each outpoint, calculate the fee-bumping cost to spend this outpoint at the specified
+    //  feerate, including bumping its ancestors. For example, if the target feerate is 10sat/vbyte
+    //  and this outpoint refers to a mempool transaction at 3sat/vbyte, the bump fee includes the
+    //  cost to bump the mempool transaction to 10sat/vbyte (i.e. 7 * mempooltx.vsize). If that
+    //  transaction also has, say, an unconfirmed parent with a feerate of 1sat/vbyte, the bump fee
+    //  includes the cost to bump the parent (i.e. 9 * parentmempooltx.vsize).
+    //
+    //  If the outpoint comes from an unconfirmed transaction that is already above the target
+    //  feerate or bumped by its descendant(s) already, it does not need to be bumped. Its bump fee
+    //  is 0. Likewise, if any of the transaction's ancestors are already bumped by a transaction
+    //  in our mempool, they are not included in the transaction's bump fee.
+    //
+    //  Also supported is bump-fee calculation in the case of replacements. If an outpoint
+    //  conflicts with another transaction in the mempool, it is assumed that the goal is to replace
+    //  that transaction. As such, the calculation will exclude the to-be-replaced transaction, but
+    //  will include the fee-bumping cost. If bump fees of descendants of the to-be-replaced
+    //  transaction are requested, the value will be 0. Fee-related RBF rules are not included as
+    //  they are logically distinct.
+    //
+    //  Any outpoints that are otherwise unavailable from the mempool (e.g. UTXOs from confirmed
+    //  transactions or transactions not yet broadcast by the wallet) are given a bump fee of 0.
+    //
+    //  If multiple outpoints come from the same transaction (which would be very rare because
+    //  it means that one transaction has multiple change outputs or paid the same wallet using multiple
+    //  outputs in the same transaction) or have shared ancestry, the bump fees are calculated
+    //  independently, i.e. as if only one of them is spent. This may result in double-fee-bumping. This
+    //  caveat can be rectified per use of the sister-function CalculateCombinedBumpFee(…).
+    virtual std::map<COutPoint, CAmount> CalculateIndividualBumpFees(const std::vector<COutPoint>& outpoints, const CFeeRate& target_feerate) = 0;
+
+    //! Calculate the combined bump fee for an input set per the same strategy
+    //  as in CalculateIndividualBumpFees(…).
+    //  Unlike CalculateIndividualBumpFees(…), this does not return individual
+    //  bump fees per outpoint, but a single bump fee for the shared ancestry.
+    //  The combined bump fee may be used to correct overestimation due to
+    //  shared ancestry by multiple UTXOs after coin selection.
+    virtual std::optional<CAmount> CalculateCombinedBumpFee(const std::vector<COutPoint>& outpoints, const CFeeRate& target_feerate) = 0;
+
     //! Get the node's package limits.
     //! Currently only returns the ancestor and descendant count limits, but could be enhanced to
     //! return more policy settings.
diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index a6d84555c0824..e0c40036d90d2 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -28,6 +28,7 @@
 #include <node/coin.h>
 #include <node/context.h>
 #include <node/interface_ui.h>
+#include <node/mini_miner.h>
 #include <node/transaction.h>
 #include <policy/feerate.h>
 #include <policy/fees.h>
@@ -665,6 +666,26 @@ class ChainImpl : public Chain
         if (!m_node.mempool) return;
         m_node.mempool->GetTransactionAncestry(txid, ancestors, descendants, ancestorsize, ancestorfees);
     }
+
+    std::map<COutPoint, CAmount> CalculateIndividualBumpFees(const std::vector<COutPoint>& outpoints, const CFeeRate& target_feerate) override
+    {
+        if (!m_node.mempool) {
+            std::map<COutPoint, CAmount> bump_fees;
+            for (const auto& outpoint : outpoints) {
+                bump_fees.emplace(std::make_pair(outpoint, 0));
+            }
+            return bump_fees;
+        }
+        return MiniMiner(*m_node.mempool, outpoints).CalculateBumpFees(target_feerate);
+    }
+
+    std::optional<CAmount> CalculateCombinedBumpFee(const std::vector<COutPoint>& outpoints, const CFeeRate& target_feerate) override
+    {
+        if (!m_node.mempool) {
+            return 0;
+        }
+        return MiniMiner(*m_node.mempool, outpoints).CalculateTotalBumpFees(target_feerate);
+    }
     void getPackageLimits(unsigned int& limit_ancestor_count, unsigned int& limit_descendant_count) override
     {
         const CTxMemPool::Limits default_limits{};
diff --git a/src/node/mini_miner.cpp b/src/node/mini_miner.cpp
index 6f253eddfae6b..2827242f96e3c 100644
--- a/src/node/mini_miner.cpp
+++ b/src/node/mini_miner.cpp
@@ -7,9 +7,7 @@
 #include <consensus/amount.h>
 #include <policy/feerate.h>
 #include <primitives/transaction.h>
-#include <timedata.h>
 #include <util/check.h>
-#include <util/moneystr.h>
 
 #include <algorithm>
 #include <numeric>
@@ -171,9 +169,8 @@ void MiniMiner::DeleteAncestorPackage(const std::set<MockEntryMap::iterator, Ite
         for (auto& descendant : it->second) {
             // If these fail, we must be double-deducting.
             Assume(descendant->second.GetModFeesWithAncestors() >= anc->second.GetModifiedFee());
-            Assume(descendant->second.vsize_with_ancestors >= anc->second.GetTxSize());
-            descendant->second.fee_with_ancestors -= anc->second.GetModifiedFee();
-            descendant->second.vsize_with_ancestors -= anc->second.GetTxSize();
+            Assume(descendant->second.GetSizeWithAncestors() >= anc->second.GetTxSize());
+            descendant->second.UpdateAncestorState(-anc->second.GetTxSize(), -anc->second.GetModifiedFee());
         }
     }
     // Delete these entries.
diff --git a/src/node/mini_miner.h b/src/node/mini_miner.h
index db07e6d1bf0df..9d9d66bf0b7f5 100644
--- a/src/node/mini_miner.h
+++ b/src/node/mini_miner.h
@@ -19,12 +19,13 @@ class MiniMinerMempoolEntry
     const CAmount fee_individual;
     const CTransactionRef tx;
     const int64_t vsize_individual;
+    CAmount fee_with_ancestors;
+    int64_t vsize_with_ancestors;
 
 // This class must be constructed while holding mempool.cs. After construction, the object's
 // methods can be called without holding that lock.
+
 public:
-    CAmount fee_with_ancestors;
-    int64_t vsize_with_ancestors;
     explicit MiniMinerMempoolEntry(CTxMemPool::txiter entry) :
         fee_individual{entry->GetModifiedFee()},
         tx{entry->GetSharedTx()},
@@ -38,6 +39,10 @@ class MiniMinerMempoolEntry
     int64_t GetTxSize() const { return vsize_individual; }
     int64_t GetSizeWithAncestors() const { return vsize_with_ancestors; }
     const CTransaction& GetTx() const LIFETIMEBOUND { return *tx; }
+    void UpdateAncestorState(int64_t vsize_change, CAmount fee_change) {
+        vsize_with_ancestors += vsize_change;
+        fee_with_ancestors += fee_change;
+    }
 };
 
 // Comparator needed for std::set<MockEntryMap::iterator>
diff --git a/src/wallet/coinselection.cpp b/src/wallet/coinselection.cpp
index d6b9b68e1f4a8..391e120932317 100644
--- a/src/wallet/coinselection.cpp
+++ b/src/wallet/coinselection.cpp
@@ -7,6 +7,7 @@
 #include <common/system.h>
 #include <consensus/amount.h>
 #include <consensus/consensus.h>
+#include <interfaces/chain.h>
 #include <logging.h>
 #include <policy/feerate.h>
 #include <util/check.h>
@@ -449,19 +450,19 @@ void OutputGroupTypeMap::Push(const OutputGroup& group, OutputType type, bool in
     }
 }
 
-CAmount GetSelectionWaste(const std::set<std::shared_ptr<COutput>>& inputs, CAmount change_cost, CAmount target, bool use_effective_value)
+CAmount SelectionResult::GetSelectionWaste(CAmount change_cost, CAmount target, bool use_effective_value)
 {
     // This function should not be called with empty inputs as that would mean the selection failed
-    assert(!inputs.empty());
+    assert(!m_selected_inputs.empty());
 
     // Always consider the cost of spending an input now vs in the future.
     CAmount waste = 0;
-    CAmount selected_effective_value = 0;
-    for (const auto& coin_ptr : inputs) {
+    for (const auto& coin_ptr : m_selected_inputs) {
         const COutput& coin = *coin_ptr;
         waste += coin.GetFee() - coin.long_term_fee;
-        selected_effective_value += use_effective_value ? coin.GetEffectiveValue() : coin.txout.nValue;
     }
+    // Bump fee of whole selection may diverge from sum of individual bump fees
+    waste -= bump_fee_group_discount;
 
     if (change_cost) {
         // Consider the cost of making change and spending it in the future
@@ -470,6 +471,7 @@ CAmount GetSelectionWaste(const std::set<std::shared_ptr<COutput>>& inputs, CAmo
         waste += change_cost;
     } else {
         // When we are not making change (change_cost == 0), consider the excess we are throwing away to fees
+        CAmount selected_effective_value = use_effective_value ? GetSelectedEffectiveValue() : GetSelectedValue();
         assert(selected_effective_value >= target);
         waste += selected_effective_value - target;
     }
@@ -488,14 +490,22 @@ CAmount GenerateChangeTarget(const CAmount payment_value, const CAmount change_f
     }
 }
 
+void SelectionResult::SetBumpFeeDiscount(const CAmount discount)
+{
+    // Overlapping ancestry can only lower the fees, not increase them
+    assert (discount >= 0);
+    bump_fee_group_discount = discount;
+}
+
+
 void SelectionResult::ComputeAndSetWaste(const CAmount min_viable_change, const CAmount change_cost, const CAmount change_fee)
 {
     const CAmount change = GetChange(min_viable_change, change_fee);
 
     if (change > 0) {
-        m_waste = GetSelectionWaste(m_selected_inputs, change_cost, m_target, m_use_effective);
+        m_waste = GetSelectionWaste(change_cost, m_target, m_use_effective);
     } else {
-        m_waste = GetSelectionWaste(m_selected_inputs, 0, m_target, m_use_effective);
+        m_waste = GetSelectionWaste(0, m_target, m_use_effective);
     }
 }
 
@@ -511,7 +521,12 @@ CAmount SelectionResult::GetSelectedValue() const
 
 CAmount SelectionResult::GetSelectedEffectiveValue() const
 {
-    return std::accumulate(m_selected_inputs.cbegin(), m_selected_inputs.cend(), CAmount{0}, [](CAmount sum, const auto& coin) { return sum + coin->GetEffectiveValue(); });
+    return std::accumulate(m_selected_inputs.cbegin(), m_selected_inputs.cend(), CAmount{0}, [](CAmount sum, const auto& coin) { return sum + coin->GetEffectiveValue(); }) + bump_fee_group_discount;
+}
+
+CAmount SelectionResult::GetTotalBumpFees() const
+{
+    return std::accumulate(m_selected_inputs.cbegin(), m_selected_inputs.cend(), CAmount{0}, [](CAmount sum, const auto& coin) { return sum + coin->ancestor_bump_fees; }) - bump_fee_group_discount;
 }
 
 void SelectionResult::Clear()
diff --git a/src/wallet/coinselection.h b/src/wallet/coinselection.h
index afd868fc89e1c..20b2461c04189 100644
--- a/src/wallet/coinselection.h
+++ b/src/wallet/coinselection.h
@@ -17,6 +17,7 @@
 
 #include <optional>
 
+
 namespace wallet {
 //! lower bound for randomly-chosen target change amount
 static constexpr CAmount CHANGE_LOWER{50000};
@@ -26,10 +27,10 @@ static constexpr CAmount CHANGE_UPPER{1000000};
 /** A UTXO under consideration for use in funding a new transaction. */
 struct COutput {
 private:
-    /** The output's value minus fees required to spend it.*/
+    /** The output's value minus fees required to spend it and bump its unconfirmed ancestors to the target feerate. */
     std::optional<CAmount> effective_value;
 
-    /** The fee required to spend this output at the transaction's target feerate. */
+    /** The fee required to spend this output at the transaction's target feerate and to bump its unconfirmed ancestors to the target feerate. */
     std::optional<CAmount> fee;
 
 public:
@@ -71,6 +72,9 @@ struct COutput {
     /** The fee required to spend this output at the consolidation feerate. */
     CAmount long_term_fee{0};
 
+    /** The fee necessary to bump this UTXO's ancestor transactions to the target feerate */
+    CAmount ancestor_bump_fees{0};
+
     COutput(const COutPoint& outpoint, const CTxOut& txout, int depth, int input_bytes, bool spendable, bool solvable, bool safe, int64_t time, bool from_me, const std::optional<CFeeRate> feerate = std::nullopt)
         : outpoint{outpoint},
           txout{txout},
@@ -83,6 +87,7 @@ struct COutput {
           from_me{from_me}
     {
         if (feerate) {
+            // base fee without considering potential unconfirmed ancestors
             fee = input_bytes < 0 ? 0 : feerate.value().GetFee(input_bytes);
             effective_value = txout.nValue - fee.value();
         }
@@ -104,6 +109,16 @@ struct COutput {
         return outpoint < rhs.outpoint;
     }
 
+    void ApplyBumpFee(CAmount bump_fee)
+    {
+        assert(bump_fee >= 0);
+        ancestor_bump_fees = bump_fee;
+        assert(fee);
+        *fee += bump_fee;
+        // Note: assert(effective_value - bump_fee == nValue - fee.value());
+        effective_value = txout.nValue - fee.value();
+    }
+
     CAmount GetFee() const
     {
         assert(fee.has_value());
@@ -275,26 +290,6 @@ struct OutputGroupTypeMap
 
 typedef std::map<CoinEligibilityFilter, OutputGroupTypeMap> FilteredOutputGroups;
 
-/** Compute the waste for this result given the cost of change
- * and the opportunity cost of spending these inputs now vs in the future.
- * If change exists, waste = change_cost + inputs * (effective_feerate - long_term_feerate)
- * If no change, waste = excess + inputs * (effective_feerate - long_term_feerate)
- * where excess = selected_effective_value - target
- * change_cost = effective_feerate * change_output_size + long_term_feerate * change_spend_size
- *
- * Note this function is separate from SelectionResult for the tests.
- *
- * @param[in] inputs The selected inputs
- * @param[in] change_cost The cost of creating change and spending it in the future.
- *                        Only used if there is change, in which case it must be positive.
- *                        Must be 0 if there is no change.
- * @param[in] target The amount targeted by the coin selection algorithm.
- * @param[in] use_effective_value Whether to use the input's effective value (when true) or the real value (when false).
- * @return The waste
- */
-[[nodiscard]] CAmount GetSelectionWaste(const std::set<std::shared_ptr<COutput>>& inputs, CAmount change_cost, CAmount target, bool use_effective_value = true);
-
-
 /** Choose a random change target for each transaction to make it harder to fingerprint the Core
  * wallet based on the change output values of transactions it creates.
  * Change target covers at least change fees and adds a random value on top of it.
@@ -336,6 +331,8 @@ struct SelectionResult
     std::optional<CAmount> m_waste;
     /** Total weight of the selected inputs */
     int m_weight{0};
+    /** How much individual inputs overestimated the bump fees for the shared ancestry */
+    CAmount bump_fee_group_discount{0};
 
     template<typename T>
     void InsertInputs(const T& inputs)
@@ -348,6 +345,22 @@ struct SelectionResult
         }
     }
 
+    /** Compute the waste for this result given the cost of change
+     * and the opportunity cost of spending these inputs now vs in the future.
+     * If change exists, waste = change_cost + inputs * (effective_feerate - long_term_feerate)
+     * If no change, waste = excess + inputs * (effective_feerate - long_term_feerate)
+     * where excess = selected_effective_value - target
+     * change_cost = effective_feerate * change_output_size + long_term_feerate * change_spend_size
+     *
+     * @param[in] change_cost The cost of creating change and spending it in the future.
+     *                        Only used if there is change, in which case it must be positive.
+     *                        Must be 0 if there is no change.
+     * @param[in] target The amount targeted by the coin selection algorithm.
+     * @param[in] use_effective_value Whether to use the input's effective value (when true) or the real value (when false).
+     * @return The waste
+     */
+    [[nodiscard]] CAmount GetSelectionWaste(CAmount change_cost, CAmount target, bool use_effective_value = true);
+
 public:
     explicit SelectionResult(const CAmount target, SelectionAlgorithm algo)
         : m_target(target), m_algo(algo) {}
@@ -359,11 +372,16 @@ struct SelectionResult
 
     [[nodiscard]] CAmount GetSelectedEffectiveValue() const;
 
+    [[nodiscard]] CAmount GetTotalBumpFees() const;
+
     void Clear();
 
     void AddInput(const OutputGroup& group);
     void AddInputs(const std::set<std::shared_ptr<COutput>>& inputs, bool subtract_fee_outputs);
 
+    /** How much individual inputs overestimated the bump fees for shared ancestries */
+    void SetBumpFeeDiscount(const CAmount discount);
+
     /** Calculates and stores the waste for this selection via GetSelectionWaste */
     void ComputeAndSetWaste(const CAmount min_viable_change, const CAmount change_cost, const CAmount change_fee);
     [[nodiscard]] CAmount GetWaste() const;
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index 3720d144ebef5..f99da926bc5a3 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -63,7 +63,7 @@ static feebumper::Result PreconditionChecks(const CWallet& wallet, const CWallet
 }
 
 //! Check if the user provided a valid feeRate
-static feebumper::Result CheckFeeRate(const CWallet& wallet, const CFeeRate& newFeerate, const int64_t maxTxSize, CAmount old_fee, std::vector<bilingual_str>& errors)
+static feebumper::Result CheckFeeRate(const CWallet& wallet, const CMutableTransaction& mtx, const CFeeRate& newFeerate, const int64_t maxTxSize, CAmount old_fee, std::vector<bilingual_str>& errors)
 {
     // check that fee rate is higher than mempool's minimum fee
     // (no point in bumping fee if we know that the new tx won't be accepted to the mempool)
@@ -80,7 +80,17 @@ static feebumper::Result CheckFeeRate(const CWallet& wallet, const CFeeRate& new
         return feebumper::Result::WALLET_ERROR;
     }
 
-    CAmount new_total_fee = newFeerate.GetFee(maxTxSize);
+    std::vector<COutPoint> reused_inputs;
+    reused_inputs.reserve(mtx.vin.size());
+    for (const CTxIn& txin : mtx.vin) {
+        reused_inputs.push_back(txin.prevout);
+    }
+
+    std::optional<CAmount> combined_bump_fee = wallet.chain().CalculateCombinedBumpFee(reused_inputs, newFeerate);
+    if (!combined_bump_fee.has_value()) {
+        errors.push_back(strprintf(Untranslated("Failed to calculate bump fees, because unconfirmed UTXOs depend on enormous cluster of unconfirmed transactions.")));
+    }
+    CAmount new_total_fee = newFeerate.GetFee(maxTxSize) + combined_bump_fee.value();
 
     CFeeRate incrementalRelayFee = std::max(wallet.chain().relayIncrementalFee(), CFeeRate(WALLET_INCREMENTAL_RELAY_FEE));
 
@@ -283,7 +293,7 @@ Result CreateRateBumpTransaction(CWallet& wallet, const uint256& txid, const CCo
         }
         temp_mtx.vout = txouts;
         const int64_t maxTxSize{CalculateMaximumSignedTxSize(CTransaction(temp_mtx), &wallet, &new_coin_control).vsize};
-        Result res = CheckFeeRate(wallet, *new_coin_control.m_feerate, maxTxSize, old_fee, errors);
+        Result res = CheckFeeRate(wallet, temp_mtx, *new_coin_control.m_feerate, maxTxSize, old_fee, errors);
         if (res != Result::OK) {
             return res;
         }
diff --git a/src/wallet/spend.cpp b/src/wallet/spend.cpp
index c0ee00e0971e2..4606c2b808ace 100644
--- a/src/wallet/spend.cpp
+++ b/src/wallet/spend.cpp
@@ -162,6 +162,7 @@ util::Result<PreSelectedInputs> FetchSelectedInputs(const CWallet& wallet, const
 {
     PreSelectedInputs result;
     const bool can_grind_r = wallet.CanGrindR();
+    std::map<COutPoint, CAmount> map_of_bump_fees = wallet.chain().CalculateIndividualBumpFees(coin_control.ListSelected(), coin_selection_params.m_effective_feerate);
     for (const COutPoint& outpoint : coin_control.ListSelected()) {
         int input_bytes = -1;
         CTxOut txout;
@@ -197,6 +198,7 @@ util::Result<PreSelectedInputs> FetchSelectedInputs(const CWallet& wallet, const
 
         /* Set some defaults for depth, spendable, solvable, safe, time, and from_me as these don't matter for preset inputs since no selection is being done. */
         COutput output(outpoint, txout, /*depth=*/ 0, input_bytes, /*spendable=*/ true, /*solvable=*/ true, /*safe=*/ true, /*time=*/ 0, /*from_me=*/ false, coin_selection_params.m_effective_feerate);
+        output.ApplyBumpFee(map_of_bump_fees.at(output.outpoint));
         result.Insert(output, coin_selection_params.m_subtract_fee_outputs);
     }
     return result;
@@ -217,6 +219,7 @@ CoinsResult AvailableCoins(const CWallet& wallet,
     const int max_depth = {coinControl ? coinControl->m_max_depth : DEFAULT_MAX_DEPTH};
     const bool only_safe = {coinControl ? !coinControl->m_include_unsafe_inputs : true};
     const bool can_grind_r = wallet.CanGrindR();
+    std::vector<COutPoint> outpoints;
 
     std::set<uint256> trusted_parents;
     for (const auto& entry : wallet.mapWallet)
@@ -334,6 +337,8 @@ CoinsResult AvailableCoins(const CWallet& wallet,
             result.Add(GetOutputType(type, is_from_p2sh),
                        COutput(outpoint, output, nDepth, input_bytes, spendable, solvable, safeTx, wtx.GetTxTime(), tx_from_me, feerate));
 
+            outpoints.push_back(outpoint);
+
             // Checks the sum amount of all UTXO's.
             if (params.min_sum_amount != MAX_MONEY) {
                 if (result.GetTotalAmount() >= params.min_sum_amount) {
@@ -348,6 +353,16 @@ CoinsResult AvailableCoins(const CWallet& wallet,
         }
     }
 
+    if (feerate.has_value()) {
+        std::map<COutPoint, CAmount> map_of_bump_fees = wallet.chain().CalculateIndividualBumpFees(outpoints, feerate.value());
+
+        for (auto& [_, outputs] : result.coins) {
+            for (auto& output : outputs) {
+                output.ApplyBumpFee(map_of_bump_fees.at(output.outpoint));
+            }
+        }
+    }
+
     return result;
 }
 
@@ -529,13 +544,13 @@ FilteredOutputGroups GroupOutputs(const CWallet& wallet,
 // Returns true if the result contains an error and the message is not empty
 static bool HasErrorMsg(const util::Result<SelectionResult>& res) { return !util::ErrorString(res).empty(); }
 
-util::Result<SelectionResult> AttemptSelection(const CAmount& nTargetValue, OutputGroupTypeMap& groups,
+util::Result<SelectionResult> AttemptSelection(interfaces::Chain& chain, const CAmount& nTargetValue, OutputGroupTypeMap& groups,
                                const CoinSelectionParams& coin_selection_params, bool allow_mixed_output_types)
 {
     // Run coin selection on each OutputType and compute the Waste Metric
     std::vector<SelectionResult> results;
     for (auto& [type, group] : groups.groups_by_type) {
-        auto result{ChooseSelectionResult(nTargetValue, group, coin_selection_params)};
+        auto result{ChooseSelectionResult(chain, nTargetValue, group, coin_selection_params)};
         // If any specific error message appears here, then something particularly wrong happened.
         if (HasErrorMsg(result)) return result; // So let's return the specific error.
         // Append the favorable result.
@@ -549,14 +564,14 @@ util::Result<SelectionResult> AttemptSelection(const CAmount& nTargetValue, Outp
     // over all available coins, which would allow mixing.
     // If TypesCount() <= 1, there is nothing to mix.
     if (allow_mixed_output_types && groups.TypesCount() > 1) {
-        return ChooseSelectionResult(nTargetValue, groups.all_groups, coin_selection_params);
+        return ChooseSelectionResult(chain, nTargetValue, groups.all_groups, coin_selection_params);
     }
     // Either mixing is not allowed and we couldn't find a solution from any single OutputType, or mixing was allowed and we still couldn't
     // find a solution using all available coins
     return util::Error();
 };
 
-util::Result<SelectionResult> ChooseSelectionResult(const CAmount& nTargetValue, Groups& groups, const CoinSelectionParams& coin_selection_params)
+util::Result<SelectionResult> ChooseSelectionResult(interfaces::Chain& chain, const CAmount& nTargetValue, Groups& groups, const CoinSelectionParams& coin_selection_params)
 {
     // Vector of results. We will choose the best one based on waste.
     std::vector<SelectionResult> results;
@@ -581,12 +596,10 @@ util::Result<SelectionResult> ChooseSelectionResult(const CAmount& nTargetValue,
 
     // The knapsack solver has some legacy behavior where it will spend dust outputs. We retain this behavior, so don't filter for positive only here.
     if (auto knapsack_result{KnapsackSolver(groups.mixed_group, nTargetValue, coin_selection_params.m_min_change_target, coin_selection_params.rng_fast, max_inputs_weight)}) {
-        knapsack_result->ComputeAndSetWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee);
         results.push_back(*knapsack_result);
     } else append_error(knapsack_result);
 
     if (auto srd_result{SelectCoinsSRD(groups.positive_group, nTargetValue, coin_selection_params.m_change_fee, coin_selection_params.rng_fast, max_inputs_weight)}) {
-        srd_result->ComputeAndSetWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee);
         results.push_back(*srd_result);
     } else append_error(srd_result);
 
@@ -596,6 +609,27 @@ util::Result<SelectionResult> ChooseSelectionResult(const CAmount& nTargetValue,
         return errors.empty() ? util::Error() : errors.front();
     }
 
+    // If the chosen input set has unconfirmed inputs, check for synergies from overlapping ancestry
+    for (auto& result : results) {
+        std::vector<COutPoint> outpoints;
+        std::set<std::shared_ptr<COutput>> coins = result.GetInputSet();
+        CAmount summed_bump_fees = 0;
+        for (auto& coin : coins) {
+            if (coin->depth > 0) continue; // Bump fees only exist for unconfirmed inputs
+            outpoints.push_back(coin->outpoint);
+            summed_bump_fees += coin->ancestor_bump_fees;
+        }
+        std::optional<CAmount> combined_bump_fee = chain.CalculateCombinedBumpFee(outpoints, coin_selection_params.m_effective_feerate);
+        if (!combined_bump_fee.has_value()) {
+            return util::Error{_("Failed to calculate bump fees, because unconfirmed UTXOs depend on enormous cluster of unconfirmed transactions.")};
+        }
+        CAmount bump_fee_overestimate = summed_bump_fees - combined_bump_fee.value();
+        if (bump_fee_overestimate) {
+            result.SetBumpFeeDiscount(bump_fee_overestimate);
+        }
+        result.ComputeAndSetWaste(coin_selection_params.min_viable_change, coin_selection_params.m_cost_of_change, coin_selection_params.m_change_fee);
+    }
+
     // Choose the result with the least waste
     // If the waste is the same, choose the one which spends more inputs.
     return *std::min_element(results.begin(), results.end());
@@ -725,7 +759,7 @@ util::Result<SelectionResult> AutomaticCoinSelection(const CWallet& wallet, Coin
         for (const auto& select_filter : ordered_filters) {
             auto it = filtered_groups.find(select_filter.filter);
             if (it == filtered_groups.end()) continue;
-            if (auto res{AttemptSelection(value_to_select, it->second,
+            if (auto res{AttemptSelection(wallet.chain(), value_to_select, it->second,
                                           coin_selection_params, select_filter.allow_mixed_output_types)}) {
                 return res; // result found
             } else {
@@ -1021,7 +1055,7 @@ static util::Result<CreatedTransactionResult> CreateTransactionInternal(
     if (nBytes == -1) {
         return util::Error{_("Missing solving data for estimating transaction size")};
     }
-    CAmount fee_needed = coin_selection_params.m_effective_feerate.GetFee(nBytes);
+    CAmount fee_needed = coin_selection_params.m_effective_feerate.GetFee(nBytes) + result.GetTotalBumpFees();
     const CAmount output_value = CalculateOutputValue(txNew);
     Assume(recipients_sum + change_amount == output_value);
     CAmount current_fee = result.GetSelectedValue() - output_value;
diff --git a/src/wallet/spend.h b/src/wallet/spend.h
index cc9ccf30118f6..407627b5f1856 100644
--- a/src/wallet/spend.h
+++ b/src/wallet/spend.h
@@ -123,6 +123,7 @@ FilteredOutputGroups GroupOutputs(const CWallet& wallet,
  * the solution (according to the waste metric) will be chosen. If a valid input cannot be found from any
  * single OutputType, fallback to running `ChooseSelectionResult()` over all available coins.
  *
+ * param@[in]  chain                     The chain interface to get information on unconfirmed UTXOs bump fees
  * param@[in]  nTargetValue              The target value
  * param@[in]  groups                    The grouped outputs mapped by coin eligibility filters
  * param@[in]  coin_selection_params     Parameters for the coin selection
@@ -132,7 +133,7 @@ FilteredOutputGroups GroupOutputs(const CWallet& wallet,
  *                                                  or (2) an specific error message if there was something particularly wrong (e.g. a selection
  *                                                  result that surpassed the tx max weight size).
  */
-util::Result<SelectionResult> AttemptSelection(const CAmount& nTargetValue, OutputGroupTypeMap& groups,
+util::Result<SelectionResult> AttemptSelection(interfaces::Chain& chain, const CAmount& nTargetValue, OutputGroupTypeMap& groups,
                         const CoinSelectionParams& coin_selection_params, bool allow_mixed_output_types);
 
 /**
@@ -140,6 +141,7 @@ util::Result<SelectionResult> AttemptSelection(const CAmount& nTargetValue, Outp
  * Multiple coin selection algorithms will be run and the input set that produces the least waste
  * (according to the waste metric) will be chosen.
  *
+ * param@[in]  chain                     The chain interface to get information on unconfirmed UTXOs bump fees
  * param@[in]  nTargetValue              The target value
  * param@[in]  groups                    The struct containing the outputs grouped by script and divided by (1) positive only outputs and (2) all outputs (positive + negative).
  * param@[in]  coin_selection_params     Parameters for the coin selection
@@ -148,7 +150,7 @@ util::Result<SelectionResult> AttemptSelection(const CAmount& nTargetValue, Outp
  *                                                  or (2) an specific error message if there was something particularly wrong (e.g. a selection
  *                                                  result that surpassed the tx max weight size).
  */
-util::Result<SelectionResult> ChooseSelectionResult(const CAmount& nTargetValue, Groups& groups, const CoinSelectionParams& coin_selection_params);
+util::Result<SelectionResult> ChooseSelectionResult(interfaces::Chain& chain, const CAmount& nTargetValue, Groups& groups, const CoinSelectionParams& coin_selection_params);
 
 // User manually selected inputs that must be part of the transaction
 struct PreSelectedInputs


Test patch:
diff --git a/src/test/miniminer_tests.cpp b/src/test/miniminer_tests.cpp
index da724f8d7b96f..f65356936b7d1 100644
--- a/src/test/miniminer_tests.cpp
+++ b/src/test/miniminer_tests.cpp
@@ -77,66 +77,66 @@ BOOST_FIXTURE_TEST_CASE(miniminer_1p1c, TestChain100Setup)
     const CAmount normal_fee{CENT/200};
     const CAmount high_fee{CENT/10};
 
-    // Create a parent tx1 and child tx2 with normal fees:
-    const auto tx1 = make_tx({COutPoint{m_coinbase_txns[0]->GetHash(), 0}}, /*num_outputs=*/2);
+    // Create a parent tx0 and child tx1 with normal fees:
+    const auto tx0 = make_tx({COutPoint{m_coinbase_txns[0]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(normal_fee).FromTx(tx0));
+    const auto tx1 = make_tx({COutPoint{tx0->GetHash(), 0}}, /*num_outputs=*/1);
     pool.addUnchecked(entry.Fee(normal_fee).FromTx(tx1));
-    const auto tx2 = make_tx({COutPoint{tx1->GetHash(), 0}}, /*num_outputs=*/1);
-    pool.addUnchecked(entry.Fee(normal_fee).FromTx(tx2));
 
-    // Create a low-feerate parent tx3 and high-feerate child tx4 (cpfp)
-    const auto tx3 = make_tx({COutPoint{m_coinbase_txns[1]->GetHash(), 0}}, /*num_outputs=*/2);
-    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx3));
-    const auto tx4 = make_tx({COutPoint{tx3->GetHash(), 0}}, /*num_outputs=*/1);
-    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx4));
+    // Create a low-feerate parent tx2 and high-feerate child tx3 (cpfp)
+    const auto tx2 = make_tx({COutPoint{m_coinbase_txns[1]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx2));
+    const auto tx3 = make_tx({COutPoint{tx2->GetHash(), 0}}, /*num_outputs=*/1);
+    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx3));
 
-    // Create a parent tx5 and child tx6 where both have low fees
-    const auto tx5 = make_tx({COutPoint{m_coinbase_txns[2]->GetHash(), 0}}, /*num_outputs=*/2);
+    // Create a parent tx4 and child tx5 where both have low fees
+    const auto tx4 = make_tx({COutPoint{m_coinbase_txns[2]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx4));
+    const auto tx5 = make_tx({COutPoint{tx4->GetHash(), 0}}, /*num_outputs=*/1);
     pool.addUnchecked(entry.Fee(low_fee).FromTx(tx5));
-    const auto tx6 = make_tx({COutPoint{tx5->GetHash(), 0}}, /*num_outputs=*/1);
-    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx6));
-    // Make tx6's modified fee much higher than its base fee. This should cause it to pass
+    // Make tx5's modified fee much higher than its base fee. This should cause it to pass
     // the fee-related checks despite being low-feerate.
-    pool.PrioritiseTransaction(tx6->GetHash(), CENT/100);
+    pool.PrioritiseTransaction(tx5->GetHash(), CENT/100);
 
-    // Create a high-feerate parent tx7, low-feerate child tx8
-    const auto tx7 = make_tx({COutPoint{m_coinbase_txns[3]->GetHash(), 0}}, /*num_outputs=*/2);
-    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx7));
-    const auto tx8 = make_tx({COutPoint{tx7->GetHash(), 0}}, /*num_outputs=*/1);
-    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx8));
+    // Create a high-feerate parent tx6, low-feerate child tx7
+    const auto tx6 = make_tx({COutPoint{m_coinbase_txns[3]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx6));
+    const auto tx7 = make_tx({COutPoint{tx6->GetHash(), 0}}, /*num_outputs=*/1);
+    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx7));
 
     std::vector<COutPoint> all_unspent_outpoints({
-        COutPoint{tx1->GetHash(), 1},
-        COutPoint{tx2->GetHash(), 0},
-        COutPoint{tx3->GetHash(), 1},
-        COutPoint{tx4->GetHash(), 0},
-        COutPoint{tx5->GetHash(), 1},
-        COutPoint{tx6->GetHash(), 0},
-        COutPoint{tx7->GetHash(), 1},
-        COutPoint{tx8->GetHash(), 0}
-    });
-    for (const auto& outpoint : all_unspent_outpoints) BOOST_CHECK(!pool.isSpent(outpoint));
-
-    std::vector<COutPoint> all_spent_outpoints({
+        COutPoint{tx0->GetHash(), 1},
         COutPoint{tx1->GetHash(), 0},
+        COutPoint{tx2->GetHash(), 1},
         COutPoint{tx3->GetHash(), 0},
+        COutPoint{tx4->GetHash(), 1},
         COutPoint{tx5->GetHash(), 0},
+        COutPoint{tx6->GetHash(), 1},
         COutPoint{tx7->GetHash(), 0}
     });
+    for (const auto& outpoint : all_unspent_outpoints) BOOST_CHECK(!pool.isSpent(outpoint));
+
+    std::vector<COutPoint> all_spent_outpoints({
+        COutPoint{tx0->GetHash(), 0},
+        COutPoint{tx2->GetHash(), 0},
+        COutPoint{tx4->GetHash(), 0},
+        COutPoint{tx6->GetHash(), 0}
+    });
     for (const auto& outpoint : all_spent_outpoints) BOOST_CHECK(pool.GetConflictTx(outpoint) != nullptr);
 
     std::vector<COutPoint> all_parent_outputs({
-        COutPoint{tx1->GetHash(), 0},
-        COutPoint{tx1->GetHash(), 1},
-        COutPoint{tx3->GetHash(), 0},
-        COutPoint{tx3->GetHash(), 1},
-        COutPoint{tx5->GetHash(), 0},
-        COutPoint{tx5->GetHash(), 1},
-        COutPoint{tx7->GetHash(), 0},
-        COutPoint{tx7->GetHash(), 1}
+        COutPoint{tx0->GetHash(), 0},
+        COutPoint{tx0->GetHash(), 1},
+        COutPoint{tx2->GetHash(), 0},
+        COutPoint{tx2->GetHash(), 1},
+        COutPoint{tx4->GetHash(), 0},
+        COutPoint{tx4->GetHash(), 1},
+        COutPoint{tx6->GetHash(), 0},
+        COutPoint{tx6->GetHash(), 1}
     });
 
 
-    std::vector<CTransactionRef> all_transactions{tx1, tx2, tx3, tx4, tx5, tx6, tx7, tx8};
+    std::vector<CTransactionRef> all_transactions{tx0, tx1, tx2, tx3, tx4, tx5, tx6, tx7};
     struct TxDimensions {
         int32_t vsize; CAmount mod_fee; CFeeRate feerate;
     };
@@ -178,47 +178,47 @@ BOOST_FIXTURE_TEST_CASE(miniminer_1p1c, TestChain100Setup)
         BOOST_CHECK(sanity_check(all_transactions, bump_fees));
         BOOST_CHECK_EQUAL(bump_fees.size(), all_unspent_outpoints.size());
 
-        // Check tx1 bumpfee: no other bumper.
-        const TxDimensions& tx1_dimensions = tx_dims.find(tx1->GetHash())->second;
-        CAmount bumpfee1 = Find(bump_fees, COutPoint{tx1->GetHash(), 1});
-        if (target_feerate <= tx1_dimensions.feerate) {
-            BOOST_CHECK_EQUAL(bumpfee1, 0);
+        // Check tx0 bumpfee: no other bumper.
+        const TxDimensions& tx0_dimensions = tx_dims.find(tx0->GetHash())->second;
+        CAmount bumpfee0 = Find(bump_fees, COutPoint{tx0->GetHash(), 1});
+        if (target_feerate <= tx0_dimensions.feerate) {
+            BOOST_CHECK_EQUAL(bumpfee0, 0);
         } else {
-            // Difference is fee to bump tx1 from current to target feerate.
-            BOOST_CHECK_EQUAL(bumpfee1, target_feerate.GetFee(tx1_dimensions.vsize) - tx1_dimensions.mod_fee);
+            // Difference is fee to bump tx0 from current to target feerate.
+            BOOST_CHECK_EQUAL(bumpfee0, target_feerate.GetFee(tx0_dimensions.vsize) - tx0_dimensions.mod_fee);
         }
 
-        // Check tx3 bumpfee: assisted by tx4.
+        // Check tx2 bumpfee: assisted by tx3.
+        const TxDimensions& tx2_dimensions = tx_dims.find(tx2->GetHash())->second;
         const TxDimensions& tx3_dimensions = tx_dims.find(tx3->GetHash())->second;
-        const TxDimensions& tx4_dimensions = tx_dims.find(tx4->GetHash())->second;
-        const CFeeRate tx3_feerate = CFeeRate(tx3_dimensions.mod_fee + tx4_dimensions.mod_fee, tx3_dimensions.vsize + tx4_dimensions.vsize);
-        CAmount bumpfee3 = Find(bump_fees, COutPoint{tx3->GetHash(), 1});
-        if (target_feerate <= tx3_feerate) {
-            // As long as target feerate is below tx4's ancestor feerate, there is no bump fee.
-            BOOST_CHECK_EQUAL(bumpfee3, 0);
+        const CFeeRate tx2_feerate = CFeeRate(tx2_dimensions.mod_fee + tx3_dimensions.mod_fee, tx2_dimensions.vsize + tx3_dimensions.vsize);
+        CAmount bumpfee2 = Find(bump_fees, COutPoint{tx2->GetHash(), 1});
+        if (target_feerate <= tx2_feerate) {
+            // As long as target feerate is below tx3's ancestor feerate, there is no bump fee.
+            BOOST_CHECK_EQUAL(bumpfee2, 0);
         } else {
-            // Difference is fee to bump tx3 from current to target feerate, without tx4.
-            BOOST_CHECK_EQUAL(bumpfee3, target_feerate.GetFee(tx3_dimensions.vsize) - tx3_dimensions.mod_fee);
+            // Difference is fee to bump tx2 from current to target feerate, without tx3.
+            BOOST_CHECK_EQUAL(bumpfee2, target_feerate.GetFee(tx2_dimensions.vsize) - tx2_dimensions.mod_fee);
         }
 
-        // If tx6’s modified fees are sufficient for tx5 and tx6 to be picked
+        // If tx5’s modified fees are sufficient for tx4 and tx5 to be picked
         // into the block, our prospective new transaction would not need to
-        // bump tx5 when using tx5’s second output. If however even tx6’s
+        // bump tx4 when using tx4’s second output. If however even tx5’s
         // modified fee (which essentially indicates "effective feerate") is
-        // not sufficient to bump tx5, using the second output of tx5 would
-        // require our transaction to bump tx5 from scratch since we evaluate
+        // not sufficient to bump tx4, using the second output of tx4 would
+        // require our transaction to bump tx4 from scratch since we evaluate
         // transaction packages per ancestor sets and do not consider multiple
         // children’s fees.
+        const TxDimensions& tx4_dimensions = tx_dims.find(tx4->GetHash())->second;
         const TxDimensions& tx5_dimensions = tx_dims.find(tx5->GetHash())->second;
-        const TxDimensions& tx6_dimensions = tx_dims.find(tx6->GetHash())->second;
-        const CFeeRate tx5_feerate = CFeeRate(tx5_dimensions.mod_fee + tx6_dimensions.mod_fee, tx5_dimensions.vsize + tx6_dimensions.vsize);
-        CAmount bumpfee5 = Find(bump_fees, COutPoint{tx5->GetHash(), 1});
-        if (target_feerate <= tx5_feerate) {
-            // As long as target feerate is below tx6's ancestor feerate, there is no bump fee.
-            BOOST_CHECK_EQUAL(bumpfee5, 0);
+        const CFeeRate tx4_feerate = CFeeRate(tx4_dimensions.mod_fee + tx5_dimensions.mod_fee, tx4_dimensions.vsize + tx5_dimensions.vsize);
+        CAmount bumpfee4 = Find(bump_fees, COutPoint{tx4->GetHash(), 1});
+        if (target_feerate <= tx4_feerate) {
+            // As long as target feerate is below tx5's ancestor feerate, there is no bump fee.
+            BOOST_CHECK_EQUAL(bumpfee4, 0);
         } else {
-            // Difference is fee to bump tx5 from current to target feerate, without tx6.
-            BOOST_CHECK_EQUAL(bumpfee5, target_feerate.GetFee(tx5_dimensions.vsize) - tx5_dimensions.mod_fee);
+            // Difference is fee to bump tx4 from current to target feerate, without tx5.
+            BOOST_CHECK_EQUAL(bumpfee4, target_feerate.GetFee(tx4_dimensions.vsize) - tx4_dimensions.mod_fee);
         }
     }
     // Spent outpoints should usually not be requested as they would not be
@@ -240,36 +240,36 @@ BOOST_FIXTURE_TEST_CASE(miniminer_1p1c, TestChain100Setup)
             // even though only one of them is in a to-be-replaced transaction.
             BOOST_CHECK(sanity_check(all_transactions, bump_fees));
 
-            // Check tx1 bumpfee: no other bumper.
-            const TxDimensions& tx1_dimensions = tx_dims.find(tx1->GetHash())->second;
-            CAmount it1_spent = Find(bump_fees, COutPoint{tx1->GetHash(), 0});
-            if (target_feerate <= tx1_dimensions.feerate) {
-                BOOST_CHECK_EQUAL(it1_spent, 0);
+            // Check tx0 bumpfee: no other bumper.
+            const TxDimensions& tx0_dimensions = tx_dims.find(tx0->GetHash())->second;
+            CAmount it0_spent = Find(bump_fees, COutPoint{tx0->GetHash(), 0});
+            if (target_feerate <= tx0_dimensions.feerate) {
+                BOOST_CHECK_EQUAL(it0_spent, 0);
             } else {
-                // Difference is fee to bump tx1 from current to target feerate.
-                BOOST_CHECK_EQUAL(it1_spent, target_feerate.GetFee(tx1_dimensions.vsize) - tx1_dimensions.mod_fee);
+                // Difference is fee to bump tx0 from current to target feerate.
+                BOOST_CHECK_EQUAL(it0_spent, target_feerate.GetFee(tx0_dimensions.vsize) - tx0_dimensions.mod_fee);
             }
 
-            // Check tx3 bumpfee: no other bumper, because tx4 is to-be-replaced.
-            const TxDimensions& tx3_dimensions = tx_dims.find(tx3->GetHash())->second;
-            const CFeeRate tx3_feerate_unbumped = tx3_dimensions.feerate;
-            auto it3_spent = Find(bump_fees, COutPoint{tx3->GetHash(), 0});
-            if (target_feerate <= tx3_feerate_unbumped) {
-                BOOST_CHECK_EQUAL(it3_spent, 0);
+            // Check tx2 bumpfee: no other bumper, because tx3 is to-be-replaced.
+            const TxDimensions& tx2_dimensions = tx_dims.find(tx2->GetHash())->second;
+            const CFeeRate tx2_feerate_unbumped = tx2_dimensions.feerate;
+            auto it2_spent = Find(bump_fees, COutPoint{tx2->GetHash(), 0});
+            if (target_feerate <= tx2_feerate_unbumped) {
+                BOOST_CHECK_EQUAL(it2_spent, 0);
             } else {
-                // Difference is fee to bump tx3 from current to target feerate, without tx4.
-                BOOST_CHECK_EQUAL(it3_spent, target_feerate.GetFee(tx3_dimensions.vsize) - tx3_dimensions.mod_fee);
+                // Difference is fee to bump tx2 from current to target feerate, without tx3.
+                BOOST_CHECK_EQUAL(it2_spent, target_feerate.GetFee(tx2_dimensions.vsize) - tx2_dimensions.mod_fee);
             }
 
-            // Check tx5 bumpfee: no other bumper, because tx6 is to-be-replaced.
-            const TxDimensions& tx5_dimensions = tx_dims.find(tx5->GetHash())->second;
-            const CFeeRate tx5_feerate_unbumped = tx5_dimensions.feerate;
-            auto it5_spent = Find(bump_fees, COutPoint{tx5->GetHash(), 0});
-            if (target_feerate <= tx5_feerate_unbumped) {
-                BOOST_CHECK_EQUAL(it5_spent, 0);
+            // Check tx4 bumpfee: no other bumper, because tx5 is to-be-replaced.
+            const TxDimensions& tx4_dimensions = tx_dims.find(tx4->GetHash())->second;
+            const CFeeRate tx4_feerate_unbumped = tx4_dimensions.feerate;
+            auto it4_spent = Find(bump_fees, COutPoint{tx4->GetHash(), 0});
+            if (target_feerate <= tx4_feerate_unbumped) {
+                BOOST_CHECK_EQUAL(it4_spent, 0);
             } else {
-                // Difference is fee to bump tx5 from current to target feerate, without tx6.
-                BOOST_CHECK_EQUAL(it5_spent, target_feerate.GetFee(tx5_dimensions.vsize) - tx5_dimensions.mod_fee);
+                // Difference is fee to bump tx4 from current to target feerate, without tx5.
+                BOOST_CHECK_EQUAL(it4_spent, target_feerate.GetFee(tx4_dimensions.vsize) - tx4_dimensions.mod_fee);
             }
         }
     }
@@ -277,145 +277,178 @@ BOOST_FIXTURE_TEST_CASE(miniminer_1p1c, TestChain100Setup)
 
 BOOST_FIXTURE_TEST_CASE(miniminer_overlap, TestChain100Setup)
 {
+/*      Tx graph for `miniminer_overlap` unit test:
+ *
+ *     coinbase_tx [mined]        ... block-chain
+ *  -------------------------------------------------
+ *      /   |   \          \      ... mempool
+ *     /    |    \         |
+ *   tx0   tx1   tx2      tx4
+ *  [low] [med] [high]   [high]
+ *     \    |    /         |
+ *      \   |   /         tx5
+ *       \  |  /         [low]
+ *         tx3          /     \
+ *        [high]       tx6    tx7
+ *                    [med]  [high]
+ *
+ *  NOTE:
+ *  -> "low"/"med"/"high" denote the _absolute_ fee of each tx
+ *  -> tx3 has 3 inputs and 3 outputs, all other txs have 1 input and 2 outputs
+ *  -> tx3's feerate is lower than tx2's, as tx3 has more weight (due to having more inputs and outputs)
+ *
+ *  -> tx2_FR = high / tx2_vsize
+ *  -> tx3_FR = high / tx3_vsize
+ *  -> tx3_ASFR = (low+med+high+high) / (tx0_vsize + tx1_vsize + tx2_vsize + tx3_vsize)
+ *  -> tx4_FR = high / tx4_vsize
+ *  -> tx6_ASFR = (high+low+med) / (tx4_vsize + tx5_vsize + tx6_vsize)
+ *  -> tx7_ASFR = (high+low+high) / (tx4_vsize + tx5_vsize + tx7_vsize) */
+
     CTxMemPool& pool = *Assert(m_node.mempool);
     LOCK2(::cs_main, pool.cs);
     TestMemPoolEntryHelper entry;
 
-    const CAmount low_fee{CENT/2000};
-    const CAmount med_fee{CENT/200};
-    const CAmount high_fee{CENT/10};
-
-    // Create 3 parents of different feerates, and 1 child spending from all 3.
-    const auto tx1 = make_tx({COutPoint{m_coinbase_txns[0]->GetHash(), 0}}, /*num_outputs=*/2);
-    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx1));
-    const auto tx2 = make_tx({COutPoint{m_coinbase_txns[1]->GetHash(), 0}}, /*num_outputs=*/2);
-    pool.addUnchecked(entry.Fee(med_fee).FromTx(tx2));
-    const auto tx3 = make_tx({COutPoint{m_coinbase_txns[2]->GetHash(), 0}}, /*num_outputs=*/2);
+    const CAmount low_fee{CENT/2000}; // 500 ṩ
+    const CAmount med_fee{CENT/200}; // 5000 ṩ
+    const CAmount high_fee{CENT/10}; // 100_000 ṩ
+
+    // Create 3 parents of different feerates, and 1 child spending outputs from all 3 parents.
+    const auto tx0 = make_tx({COutPoint{m_coinbase_txns[0]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx0));
+    const auto tx1 = make_tx({COutPoint{m_coinbase_txns[1]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(med_fee).FromTx(tx1));
+    const auto tx2 = make_tx({COutPoint{m_coinbase_txns[2]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx2));
+    const auto tx3 = make_tx({COutPoint{tx0->GetHash(), 0}, COutPoint{tx1->GetHash(), 0}, COutPoint{tx2->GetHash(), 0}}, /*num_outputs=*/3);
     pool.addUnchecked(entry.Fee(high_fee).FromTx(tx3));
-    const auto tx4 = make_tx({COutPoint{tx1->GetHash(), 0}, COutPoint{tx2->GetHash(), 0}, COutPoint{tx3->GetHash(), 0}}, /*num_outputs=*/3);
-    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx4));
 
     // Create 1 grandparent and 1 parent, then 2 children.
-    const auto tx5 = make_tx({COutPoint{m_coinbase_txns[3]->GetHash(), 0}}, /*num_outputs=*/2);
-    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx5));
-    const auto tx6 = make_tx({COutPoint{tx5->GetHash(), 0}}, /*num_outputs=*/3);
-    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx6));
-    const auto tx7 = make_tx({COutPoint{tx6->GetHash(), 0}}, /*num_outputs=*/2);
-    pool.addUnchecked(entry.Fee(med_fee).FromTx(tx7));
-    const auto tx8 = make_tx({COutPoint{tx6->GetHash(), 1}}, /*num_outputs=*/2);
-    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx8));
-
-    std::vector<CTransactionRef> all_transactions{tx1, tx2, tx3, tx4, tx5, tx6, tx7, tx8};
+    const auto tx4 = make_tx({COutPoint{m_coinbase_txns[3]->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx4));
+    const auto tx5 = make_tx({COutPoint{tx4->GetHash(), 0}}, /*num_outputs=*/3);
+    pool.addUnchecked(entry.Fee(low_fee).FromTx(tx5));
+    const auto tx6 = make_tx({COutPoint{tx5->GetHash(), 0}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(med_fee).FromTx(tx6));
+    const auto tx7 = make_tx({COutPoint{tx5->GetHash(), 1}}, /*num_outputs=*/2);
+    pool.addUnchecked(entry.Fee(high_fee).FromTx(tx7));
+
+    std::vector<CTransactionRef> all_transactions{tx0, tx1, tx2, tx3, tx4, tx5, tx6, tx7};
     std::vector<int64_t> tx_vsizes;
     tx_vsizes.reserve(all_transactions.size());
     for (const auto& tx : all_transactions) tx_vsizes.push_back(GetVirtualTransactionSize(*tx));
 
     std::vector<COutPoint> all_unspent_outpoints({
+        COutPoint{tx0->GetHash(), 1},
         COutPoint{tx1->GetHash(), 1},
         COutPoint{tx2->GetHash(), 1},
+        COutPoint{tx3->GetHash(), 0},
         COutPoint{tx3->GetHash(), 1},
-        COutPoint{tx4->GetHash(), 0},
+        COutPoint{tx3->GetHash(), 2},
         COutPoint{tx4->GetHash(), 1},
-        COutPoint{tx4->GetHash(), 2},
-        COutPoint{tx5->GetHash(), 1},
-        COutPoint{tx6->GetHash(), 2},
-        COutPoint{tx7->GetHash(), 0},
-        COutPoint{tx8->GetHash(), 0}
+        COutPoint{tx5->GetHash(), 2},
+        COutPoint{tx6->GetHash(), 0},
+        COutPoint{tx7->GetHash(), 0}
     });
     for (const auto& outpoint : all_unspent_outpoints) BOOST_CHECK(!pool.isSpent(outpoint));
 
-    const auto tx3_feerate = CFeeRate(high_fee, tx_vsizes[2]);
-    const auto tx4_feerate = CFeeRate(high_fee, tx_vsizes[3]);
-    // tx4's feerate is lower than tx3's. same fee, different weight.
-    BOOST_CHECK(tx3_feerate > tx4_feerate);
-    const auto tx4_anc_feerate = CFeeRate(low_fee + med_fee + high_fee, tx_vsizes[0] + tx_vsizes[1] + tx_vsizes[3]);
-    const auto tx5_feerate = CFeeRate(high_fee, tx_vsizes[4]);
-    const auto tx7_anc_feerate = CFeeRate(low_fee + med_fee, tx_vsizes[5] + tx_vsizes[6]);
-    const auto tx8_anc_feerate = CFeeRate(low_fee + high_fee, tx_vsizes[5] + tx_vsizes[7]);
-    BOOST_CHECK(tx5_feerate > tx7_anc_feerate);
-    BOOST_CHECK(tx5_feerate > tx8_anc_feerate);
+    const auto tx2_feerate = CFeeRate(high_fee, tx_vsizes[2]);
+    const auto tx3_feerate = CFeeRate(high_fee, tx_vsizes[3]);
+    // tx3's feerate is lower than tx2's. same fee, different weight.
+    BOOST_CHECK(tx2_feerate > tx3_feerate);
+    const auto tx3_anc_feerate = CFeeRate(low_fee + med_fee + high_fee + high_fee, tx_vsizes[0] + tx_vsizes[1] + tx_vsizes[2] + tx_vsizes[3]);
+    const auto tx3_iter = pool.GetIter(tx3->GetHash());
+    BOOST_CHECK(tx3_anc_feerate == CFeeRate(tx3_iter.value()->GetModFeesWithAncestors(), tx3_iter.value()->GetSizeWithAncestors()));
+    const auto tx4_feerate = CFeeRate(high_fee, tx_vsizes[4]);
+    const auto tx6_anc_feerate = CFeeRate(high_fee + low_fee + med_fee, tx_vsizes[4] + tx_vsizes[5] + tx_vsizes[6]);
+    const auto tx6_iter = pool.GetIter(tx6->GetHash());
+    BOOST_CHECK(tx6_anc_feerate == CFeeRate(tx6_iter.value()->GetModFeesWithAncestors(), tx6_iter.value()->GetSizeWithAncestors()));
+    const auto tx7_anc_feerate = CFeeRate(high_fee + low_fee + high_fee, tx_vsizes[4] + tx_vsizes[5] + tx_vsizes[7]);
+    const auto tx7_iter = pool.GetIter(tx7->GetHash());
+    BOOST_CHECK(tx7_anc_feerate == CFeeRate(tx7_iter.value()->GetModFeesWithAncestors(), tx7_iter.value()->GetSizeWithAncestors()));
+    BOOST_CHECK(tx4_feerate > tx6_anc_feerate);
+    BOOST_CHECK(tx4_feerate > tx7_anc_feerate);
 
     // Extremely high feerate: everybody's bumpfee is from their full ancestor set.
     {
         node::MiniMiner mini_miner(pool, all_unspent_outpoints);
         const CFeeRate very_high_feerate(COIN);
-        BOOST_CHECK(tx4_anc_feerate < very_high_feerate);
+        BOOST_CHECK(tx3_anc_feerate < very_high_feerate);
         BOOST_CHECK(mini_miner.IsReadyToCalculate());
         auto bump_fees = mini_miner.CalculateBumpFees(very_high_feerate);
         BOOST_CHECK_EQUAL(bump_fees.size(), all_unspent_outpoints.size());
         BOOST_CHECK(!mini_miner.IsReadyToCalculate());
         BOOST_CHECK(sanity_check(all_transactions, bump_fees));
-        const auto tx1_bumpfee = bump_fees.find(COutPoint{tx1->GetHash(), 1});
-        BOOST_CHECK(tx1_bumpfee != bump_fees.end());
-        BOOST_CHECK_EQUAL(tx1_bumpfee->second, very_high_feerate.GetFee(tx_vsizes[0]) - low_fee);
-        const auto tx4_bumpfee = bump_fees.find(COutPoint{tx4->GetHash(), 0});
-        BOOST_CHECK(tx4_bumpfee != bump_fees.end());
-        BOOST_CHECK_EQUAL(tx4_bumpfee->second,
+        const auto tx0_bumpfee = bump_fees.find(COutPoint{tx0->GetHash(), 1});
+        BOOST_CHECK(tx0_bumpfee != bump_fees.end());
+        BOOST_CHECK_EQUAL(tx0_bumpfee->second, very_high_feerate.GetFee(tx_vsizes[0]) - low_fee);
+        const auto tx3_bumpfee = bump_fees.find(COutPoint{tx3->GetHash(), 0});
+        BOOST_CHECK(tx3_bumpfee != bump_fees.end());
+        BOOST_CHECK_EQUAL(tx3_bumpfee->second,
             very_high_feerate.GetFee(tx_vsizes[0] + tx_vsizes[1] + tx_vsizes[2] + tx_vsizes[3]) - (low_fee + med_fee + high_fee + high_fee));
+        const auto tx6_bumpfee = bump_fees.find(COutPoint{tx6->GetHash(), 0});
+        BOOST_CHECK(tx6_bumpfee != bump_fees.end());
+        BOOST_CHECK_EQUAL(tx6_bumpfee->second,
+            very_high_feerate.GetFee(tx_vsizes[4] + tx_vsizes[5] + tx_vsizes[6]) - (high_fee + low_fee + med_fee));
         const auto tx7_bumpfee = bump_fees.find(COutPoint{tx7->GetHash(), 0});
         BOOST_CHECK(tx7_bumpfee != bump_fees.end());
         BOOST_CHECK_EQUAL(tx7_bumpfee->second,
-            very_high_feerate.GetFee(tx_vsizes[4] + tx_vsizes[5] + tx_vsizes[6]) - (high_fee + low_fee + med_fee));
-        const auto tx8_bumpfee = bump_fees.find(COutPoint{tx8->GetHash(), 0});
-        BOOST_CHECK(tx8_bumpfee != bump_fees.end());
-        BOOST_CHECK_EQUAL(tx8_bumpfee->second,
             very_high_feerate.GetFee(tx_vsizes[4] + tx_vsizes[5] + tx_vsizes[7]) - (high_fee + low_fee + high_fee));
-        // Total fees: if spending multiple outputs from tx4 don't double-count fees.
-        node::MiniMiner mini_miner_total_tx4(pool, {COutPoint{tx4->GetHash(), 0}, COutPoint{tx4->GetHash(), 1}});
-        BOOST_CHECK(mini_miner_total_tx4.IsReadyToCalculate());
-        const auto tx4_bump_fee = mini_miner_total_tx4.CalculateTotalBumpFees(very_high_feerate);
-        BOOST_CHECK(!mini_miner_total_tx4.IsReadyToCalculate());
-        BOOST_CHECK(tx4_bump_fee.has_value());
-        BOOST_CHECK_EQUAL(tx4_bump_fee.value(),
+        // Total fees: if spending multiple outputs from tx3 don't double-count fees.
+        node::MiniMiner mini_miner_total_tx3(pool, {COutPoint{tx3->GetHash(), 0}, COutPoint{tx3->GetHash(), 1}});
+        BOOST_CHECK(mini_miner_total_tx3.IsReadyToCalculate());
+        const auto tx3_bump_fee = mini_miner_total_tx3.CalculateTotalBumpFees(very_high_feerate);
+        BOOST_CHECK(!mini_miner_total_tx3.IsReadyToCalculate());
+        BOOST_CHECK(tx3_bump_fee.has_value());
+        BOOST_CHECK_EQUAL(tx3_bump_fee.value(),
             very_high_feerate.GetFee(tx_vsizes[0] + tx_vsizes[1] + tx_vsizes[2] + tx_vsizes[3]) - (low_fee + med_fee + high_fee + high_fee));
-        // Total fees: if spending both tx7 and tx8, don't double-count fees.
-        node::MiniMiner mini_miner_tx7_tx8(pool, {COutPoint{tx7->GetHash(), 0}, COutPoint{tx8->GetHash(), 0}});
-        BOOST_CHECK(mini_miner_tx7_tx8.IsReadyToCalculate());
-        const auto tx7_tx8_bumpfee = mini_miner_tx7_tx8.CalculateTotalBumpFees(very_high_feerate);
-        BOOST_CHECK(!mini_miner_tx7_tx8.IsReadyToCalculate());
-        BOOST_CHECK(tx7_tx8_bumpfee.has_value());
-        BOOST_CHECK_EQUAL(tx7_tx8_bumpfee.value(),
+        // Total fees: if spending both tx6 and tx7, don't double-count fees.
+        node::MiniMiner mini_miner_tx6_tx7(pool, {COutPoint{tx6->GetHash(), 0}, COutPoint{tx7->GetHash(), 0}});
+        BOOST_CHECK(mini_miner_tx6_tx7.IsReadyToCalculate());
+        const auto tx6_tx7_bumpfee = mini_miner_tx6_tx7.CalculateTotalBumpFees(very_high_feerate);
+        BOOST_CHECK(!mini_miner_tx6_tx7.IsReadyToCalculate());
+        BOOST_CHECK(tx6_tx7_bumpfee.has_value());
+        BOOST_CHECK_EQUAL(tx6_tx7_bumpfee.value(),
             very_high_feerate.GetFee(tx_vsizes[4] + tx_vsizes[5] + tx_vsizes[6] + tx_vsizes[7]) - (high_fee + low_fee + med_fee + high_fee));
     }
-    // Feerate just below tx5: tx7 and tx8 have different bump fees.
+    // Feerate just below tx4: tx6 and tx7 have different bump fees.
     {
-        const auto just_below_tx5 = CFeeRate(tx5_feerate.GetFeePerK() - 5);
+        const auto just_below_tx4 = CFeeRate(tx4_feerate.GetFeePerK() - 5);
         node::MiniMiner mini_miner(pool, all_unspent_outpoints);
         BOOST_CHECK(mini_miner.IsReadyToCalculate());
-        auto bump_fees = mini_miner.CalculateBumpFees(just_below_tx5);
+        auto bump_fees = mini_miner.CalculateBumpFees(just_below_tx4);
         BOOST_CHECK(!mini_miner.IsReadyToCalculate());
         BOOST_CHECK_EQUAL(bump_fees.size(), all_unspent_outpoints.size());
         BOOST_CHECK(sanity_check(all_transactions, bump_fees));
+        const auto tx6_bumpfee = bump_fees.find(COutPoint{tx6->GetHash(), 0});
+        BOOST_CHECK(tx6_bumpfee != bump_fees.end());
+        BOOST_CHECK_EQUAL(tx6_bumpfee->second, just_below_tx4.GetFee(tx_vsizes[5] + tx_vsizes[6]) - (low_fee + med_fee));
         const auto tx7_bumpfee = bump_fees.find(COutPoint{tx7->GetHash(), 0});
         BOOST_CHECK(tx7_bumpfee != bump_fees.end());
-        BOOST_CHECK_EQUAL(tx7_bumpfee->second, just_below_tx5.GetFee(tx_vsizes[5] + tx_vsizes[6]) - (low_fee + med_fee));
-        const auto tx8_bumpfee = bump_fees.find(COutPoint{tx8->GetHash(), 0});
-        BOOST_CHECK(tx8_bumpfee != bump_fees.end());
-        BOOST_CHECK_EQUAL(tx8_bumpfee->second, just_below_tx5.GetFee(tx_vsizes[5] + tx_vsizes[7]) - (low_fee + high_fee));
-        // Total fees: if spending both tx7 and tx8, don't double-count fees.
-        node::MiniMiner mini_miner_tx7_tx8(pool, {COutPoint{tx7->GetHash(), 0}, COutPoint{tx8->GetHash(), 0}});
-        BOOST_CHECK(mini_miner_tx7_tx8.IsReadyToCalculate());
-        const auto tx7_tx8_bumpfee = mini_miner_tx7_tx8.CalculateTotalBumpFees(just_below_tx5);
-        BOOST_CHECK(!mini_miner_tx7_tx8.IsReadyToCalculate());
-        BOOST_CHECK(tx7_tx8_bumpfee.has_value());
-        BOOST_CHECK_EQUAL(tx7_tx8_bumpfee.value(), just_below_tx5.GetFee(tx_vsizes[5] + tx_vsizes[6]) - (low_fee + med_fee));
+        BOOST_CHECK_EQUAL(tx7_bumpfee->second, just_below_tx4.GetFee(tx_vsizes[5] + tx_vsizes[7]) - (low_fee + high_fee));
+        // Total fees: if spending both tx6 and tx7, don't double-count fees.
+        node::MiniMiner mini_miner_tx6_tx7(pool, {COutPoint{tx6->GetHash(), 0}, COutPoint{tx7->GetHash(), 0}});
+        BOOST_CHECK(mini_miner_tx6_tx7.IsReadyToCalculate());
+        const auto tx6_tx7_bumpfee = mini_miner_tx6_tx7.CalculateTotalBumpFees(just_below_tx4);
+        BOOST_CHECK(!mini_miner_tx6_tx7.IsReadyToCalculate());
+        BOOST_CHECK(tx6_tx7_bumpfee.has_value());
+        BOOST_CHECK_EQUAL(tx6_tx7_bumpfee.value(), just_below_tx4.GetFee(tx_vsizes[5] + tx_vsizes[6]) - (low_fee + med_fee));
     }
-    // Feerate between tx7 and tx8's ancestor feerates: don't need to bump tx6 because tx8 already does.
+    // Feerate between tx6 and tx7's ancestor feerates: don't need to bump tx5 because tx7 already does.
     {
-        const auto just_above_tx7 = CFeeRate(med_fee + 10, tx_vsizes[6]);
-        BOOST_CHECK(just_above_tx7 <= CFeeRate(low_fee + high_fee, tx_vsizes[5] + tx_vsizes[7]));
+        const auto just_above_tx6 = CFeeRate(med_fee + 10, tx_vsizes[6]);
+        BOOST_CHECK(just_above_tx6 <= CFeeRate(low_fee + high_fee, tx_vsizes[5] + tx_vsizes[7]));
         node::MiniMiner mini_miner(pool, all_unspent_outpoints);
         BOOST_CHECK(mini_miner.IsReadyToCalculate());
-        auto bump_fees = mini_miner.CalculateBumpFees(just_above_tx7);
+        auto bump_fees = mini_miner.CalculateBumpFees(just_above_tx6);
         BOOST_CHECK(!mini_miner.IsReadyToCalculate());
         BOOST_CHECK_EQUAL(bump_fees.size(), all_unspent_outpoints.size());
         BOOST_CHECK(sanity_check(all_transactions, bump_fees));
+        const auto tx6_bumpfee = bump_fees.find(COutPoint{tx6->GetHash(), 0});
+        BOOST_CHECK(tx6_bumpfee != bump_fees.end());
+        BOOST_CHECK_EQUAL(tx6_bumpfee->second, just_above_tx6.GetFee(tx_vsizes[6]) - (med_fee));
         const auto tx7_bumpfee = bump_fees.find(COutPoint{tx7->GetHash(), 0});
         BOOST_CHECK(tx7_bumpfee != bump_fees.end());
-        BOOST_CHECK_EQUAL(tx7_bumpfee->second, just_above_tx7.GetFee(tx_vsizes[6]) - (med_fee));
-        const auto tx8_bumpfee = bump_fees.find(COutPoint{tx8->GetHash(), 0});
-        BOOST_CHECK(tx8_bumpfee != bump_fees.end());
-        BOOST_CHECK_EQUAL(tx8_bumpfee->second, 0);
+        BOOST_CHECK_EQUAL(tx7_bumpfee->second, 0);
     }
 }
 BOOST_FIXTURE_TEST_CASE(calculate_cluster, TestChain100Setup)
@@ -445,12 +478,12 @@ BOOST_FIXTURE_TEST_CASE(calculate_cluster, TestChain100Setup)
     const auto cluster_501 = pool.GatherClusters({tx_501->GetHash()});
     BOOST_CHECK_EQUAL(cluster_501.size(), 0);
 
-    // Zig Zag cluster:
-    // txp0     txp1     txp2    ...  txp48  txp49
-    //    \    /    \   /   \            \   /
-    //     txc0     txc1    txc2  ...    txc48
-    // Note that each transaction's ancestor size is 1 or 3, and each descendant size is 1, 2 or 3.
-    // However, all of these transactions are in the same cluster.
+    /* Zig Zag cluster:
+     * txp0     txp1     txp2    ...  txp48  txp49
+     *    \    /    \   /   \            \   /
+     *     txc0     txc1    txc2  ...    txc48
+     * Note that each transaction's ancestor size is 1 or 3, and each descendant size is 1, 2 or 3.
+     * However, all of these transactions are in the same cluster. */
     std::vector<uint256> zigzag_txids;
     for (auto p{0}; p < 50; ++p) {
         const auto txp = make_tx({COutPoint{GetRandHash(), 0}}, /*num_outputs=*/2);
diff --git a/src/wallet/test/coinselector_tests.cpp b/src/wallet/test/coinselector_tests.cpp
index c8283f453a055..9569210ba0630 100644
--- a/src/wallet/test/coinselector_tests.cpp
+++ b/src/wallet/test/coinselector_tests.cpp
@@ -58,15 +58,17 @@ static void add_coin(const CAmount& nValue, int nInput, SelectionResult& result)
     result.AddInput(group);
 }
 
-static void add_coin(const CAmount& nValue, int nInput, CoinSet& set, CAmount fee = 0, CAmount long_term_fee = 0)
+static void add_coin(const CAmount& nValue, int nInput, SelectionResult& result, CAmount fee, CAmount long_term_fee)
 {
     CMutableTransaction tx;
     tx.vout.resize(nInput + 1);
     tx.vout[nInput].nValue = nValue;
     tx.nLockTime = nextLockTime++;        // so all transactions get different hashes
-    COutput coin(COutPoint(tx.GetHash(), nInput), tx.vout.at(nInput), /*depth=*/ 1, /*input_bytes=*/ 148, /*spendable=*/ true, /*solvable=*/ true, /*safe=*/ true, /*time=*/ 0, /*from_me=*/ false, fee);
-    coin.long_term_fee = long_term_fee;
-    set.insert(std::make_shared<COutput>(coin));
+    std::shared_ptr<COutput> coin = std::make_shared<COutput>(COutPoint(tx.GetHash(), nInput), tx.vout.at(nInput), /*depth=*/ 1, /*input_bytes=*/ 148, /*spendable=*/ true, /*solvable=*/ true, /*safe=*/ true, /*time=*/ 0, /*from_me=*/ false, fee);
+    OutputGroup group;
+    group.Insert(coin, /*ancestors=*/ 0, /*descendants=*/ 0);
+    coin->long_term_fee = long_term_fee; // group.Insert() will modify long_term_fee, so we need to set it afterwards
+    result.AddInput(group);
 }
 
 static void add_coin(CoinsResult& available_coins, CWallet& wallet, const CAmount& nValue, CFeeRate feerate = CFeeRate(0), int nAge = 6*24, bool fIsFromMe = false, int nInput =0, bool spendable = false, int custom_size = 0)
@@ -827,7 +829,6 @@ BOOST_AUTO_TEST_CASE(SelectCoins_test)
 
 BOOST_AUTO_TEST_CASE(waste_test)
 {
-    CoinSet selection;
     const CAmount fee{100};
     const CAmount change_cost{125};
     const CAmount fee_diff{40};
@@ -835,92 +836,179 @@ BOOST_AUTO_TEST_CASE(waste_test)
     const CAmount target{2 * COIN};
     const CAmount excess{in_amt - fee * 2 - target};
 
-    // Waste with change is the change cost and difference between fee and long term fee
-    add_coin(1 * COIN, 1, selection, fee, fee - fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee - fee_diff);
-    const CAmount waste1 = GetSelectionWaste(selection, change_cost, target);
-    BOOST_CHECK_EQUAL(fee_diff * 2 + change_cost, waste1);
-    selection.clear();
-
-    // Waste without change is the excess and difference between fee and long term fee
-    add_coin(1 * COIN, 1, selection, fee, fee - fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee - fee_diff);
-    const CAmount waste_nochange1 = GetSelectionWaste(selection, 0, target);
-    BOOST_CHECK_EQUAL(fee_diff * 2 + excess, waste_nochange1);
-    selection.clear();
-
-    // Waste with change and fee == long term fee is just cost of change
-    add_coin(1 * COIN, 1, selection, fee, fee);
-    add_coin(2 * COIN, 2, selection, fee, fee);
-    BOOST_CHECK_EQUAL(change_cost, GetSelectionWaste(selection, change_cost, target));
-    selection.clear();
-
-    // Waste without change and fee == long term fee is just the excess
-    add_coin(1 * COIN, 1, selection, fee, fee);
-    add_coin(2 * COIN, 2, selection, fee, fee);
-    BOOST_CHECK_EQUAL(excess, GetSelectionWaste(selection, 0, target));
-    selection.clear();
-
-    // Waste will be greater when fee is greater, but long term fee is the same
-    add_coin(1 * COIN, 1, selection, fee * 2, fee - fee_diff);
-    add_coin(2 * COIN, 2, selection, fee * 2, fee - fee_diff);
-    const CAmount waste2 = GetSelectionWaste(selection, change_cost, target);
-    BOOST_CHECK_GT(waste2, waste1);
-    selection.clear();
-
-    // Waste with change is the change cost and difference between fee and long term fee
-    // With long term fee greater than fee, waste should be less than when long term fee is less than fee
-    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
-    const CAmount waste3 = GetSelectionWaste(selection, change_cost, target);
-    BOOST_CHECK_EQUAL(fee_diff * -2 + change_cost, waste3);
-    BOOST_CHECK_LT(waste3, waste1);
-    selection.clear();
-
-    // Waste without change is the excess and difference between fee and long term fee
-    // With long term fee greater than fee, waste should be less than when long term fee is less than fee
-    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
-    const CAmount waste_nochange2 = GetSelectionWaste(selection, 0, target);
-    BOOST_CHECK_EQUAL(fee_diff * -2 + excess, waste_nochange2);
-    BOOST_CHECK_LT(waste_nochange2, waste_nochange1);
-    selection.clear();
-
-    // No Waste when fee == long_term_fee, no change, and no excess
-    add_coin(1 * COIN, 1, selection, fee, fee);
-    add_coin(2 * COIN, 2, selection, fee, fee);
-    const CAmount exact_target{in_amt - fee * 2};
-    BOOST_CHECK_EQUAL(0, GetSelectionWaste(selection, /*change_cost=*/0, exact_target));
-    selection.clear();
-
-    // No Waste when (fee - long_term_fee) == (-cost_of_change), and no excess
-    const CAmount new_change_cost{fee_diff * 2};
-    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
-    BOOST_CHECK_EQUAL(0, GetSelectionWaste(selection, new_change_cost, target));
-    selection.clear();
-
-    // No Waste when (fee - long_term_fee) == (-excess), no change cost
-    const CAmount new_target{in_amt - fee * 2 - fee_diff * 2};
-    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
-    BOOST_CHECK_EQUAL(0, GetSelectionWaste(selection, /*change_cost=*/ 0, new_target));
-    selection.clear();
-
-    // Negative waste when the long term fee is greater than the current fee and the selected value == target
-    const CAmount exact_target1{3 * COIN - 2 * fee};
-    const CAmount target_waste1{-2 * fee_diff}; // = (2 * fee) - (2 * (fee + fee_diff))
-    add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
-    BOOST_CHECK_EQUAL(target_waste1, GetSelectionWaste(selection, /*change_cost=*/ 0, exact_target1));
-    selection.clear();
-
-    // Negative waste when the long term fee is greater than the current fee and change_cost < - (inputs * (fee - long_term_fee))
-    const CAmount large_fee_diff{90};
-    const CAmount target_waste2{-2 * large_fee_diff + change_cost}; // = (2 * fee) - (2 * (fee + large_fee_diff)) + change_cost
-    add_coin(1 * COIN, 1, selection, fee, fee + large_fee_diff);
-    add_coin(2 * COIN, 2, selection, fee, fee + large_fee_diff);
-    BOOST_CHECK_EQUAL(target_waste2, GetSelectionWaste(selection, change_cost, target));
+    // The following tests that the waste is calculated correctly in various scenarios.
+    // ComputeAndSetWaste will first determine the size of the change output. We don't really
+    // care about the change and just want to use the variant that always includes the change_cost,
+    // so min_viable_change and change_fee are set to 0 to ensure that.
+    {
+        // Waste with change is the change cost and difference between fee and long term fee
+        SelectionResult selection1{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection1, fee, fee - fee_diff);
+        add_coin(2 * COIN, 2, selection1, fee, fee - fee_diff);
+        selection1.ComputeAndSetWaste(/*min_viable_change=*/0, change_cost, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(fee_diff * 2 + change_cost, selection1.GetWaste());
+
+        // Waste will be greater when fee is greater, but long term fee is the same
+        SelectionResult selection2{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection2, fee * 2, fee - fee_diff);
+        add_coin(2 * COIN, 2, selection2, fee * 2, fee - fee_diff);
+        selection2.ComputeAndSetWaste(/*min_viable_change=*/0, change_cost, /*change_fee=*/0);
+        BOOST_CHECK_GT(selection2.GetWaste(), selection1.GetWaste());
+
+        // Waste with change is the change cost and difference between fee and long term fee
+        // With long term fee greater than fee, waste should be less than when long term fee is less than fee
+        SelectionResult selection3{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection3, fee, fee + fee_diff);
+        add_coin(2 * COIN, 2, selection3, fee, fee + fee_diff);
+        selection3.ComputeAndSetWaste(/*min_viable_change=*/0, change_cost, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(fee_diff * -2 + change_cost, selection3.GetWaste());
+        BOOST_CHECK_LT(selection3.GetWaste(), selection1.GetWaste());
+    }
+
+    {
+        // Waste without change is the excess and difference between fee and long term fee
+        SelectionResult selection_nochange1{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection_nochange1, fee, fee - fee_diff);
+        add_coin(2 * COIN, 2, selection_nochange1, fee, fee - fee_diff);
+        selection_nochange1.ComputeAndSetWaste(/*min_viable_change=*/0, /*change_cost=*/0, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(fee_diff * 2 + excess, selection_nochange1.GetWaste());
+
+        // Waste without change is the excess and difference between fee and long term fee
+        // With long term fee greater than fee, waste should be less than when long term fee is less than fee
+        SelectionResult selection_nochange2{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection_nochange2, fee, fee + fee_diff);
+        add_coin(2 * COIN, 2, selection_nochange2, fee, fee + fee_diff);
+        selection_nochange2.ComputeAndSetWaste(/*min_viable_change=*/0, /*change_cost=*/0, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(fee_diff * -2 + excess, selection_nochange2.GetWaste());
+        BOOST_CHECK_LT(selection_nochange2.GetWaste(), selection_nochange1.GetWaste());
+    }
+
+    {
+        // Waste with change and fee == long term fee is just cost of change
+        SelectionResult selection{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection, fee, fee);
+        add_coin(2 * COIN, 2, selection, fee, fee);
+        selection.ComputeAndSetWaste(/*min_viable_change=*/0, change_cost, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(change_cost, selection.GetWaste());
+    }
+
+    {
+        // Waste without change and fee == long term fee is just the excess
+        SelectionResult selection{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection, fee, fee);
+        add_coin(2 * COIN, 2, selection, fee, fee);
+        selection.ComputeAndSetWaste(/*min_viable_change=*/0, /*change_cost=*/0, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(excess, selection.GetWaste());
+    }
+
+    {
+        // No Waste when fee == long_term_fee, no change, and no excess
+        const CAmount exact_target{in_amt - fee * 2};
+        SelectionResult selection{exact_target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection, fee, fee);
+        add_coin(2 * COIN, 2, selection, fee, fee);
+        selection.ComputeAndSetWaste(/*min_viable_change=*/0, /*change_cost=*/0, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(0, selection.GetWaste());
+    }
+
+    {
+        // No Waste when (fee - long_term_fee) == (-cost_of_change), and no excess
+        SelectionResult selection{target, SelectionAlgorithm::MANUAL};
+        const CAmount new_change_cost{fee_diff * 2};
+        add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
+        add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
+        selection.ComputeAndSetWaste(/*min_viable_change=*/0, new_change_cost, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(0, selection.GetWaste());
+    }
+
+    {
+        // No Waste when (fee - long_term_fee) == (-excess), no change cost
+        const CAmount new_target{in_amt - fee * 2 - fee_diff * 2};
+        SelectionResult selection{new_target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
+        add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
+        selection.ComputeAndSetWaste(/*min_viable_change=*/0, /*change_cost=*/0, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(0, selection.GetWaste());
+    }
+
+    {
+        // Negative waste when the long term fee is greater than the current fee and the selected value == target
+        const CAmount exact_target{3 * COIN - 2 * fee};
+        SelectionResult selection{exact_target, SelectionAlgorithm::MANUAL};
+        const CAmount target_waste1{-2 * fee_diff}; // = (2 * fee) - (2 * (fee + fee_diff))
+        add_coin(1 * COIN, 1, selection, fee, fee + fee_diff);
+        add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
+        selection.ComputeAndSetWaste(/*min_viable_change=*/0, /*change_cost=*/0, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(target_waste1, selection.GetWaste());
+    }
+
+    {
+        // Negative waste when the long term fee is greater than the current fee and change_cost < - (inputs * (fee - long_term_fee))
+        SelectionResult selection{target, SelectionAlgorithm::MANUAL};
+        const CAmount large_fee_diff{90};
+        const CAmount target_waste2{-2 * large_fee_diff + change_cost}; // = (2 * fee) - (2 * (fee + large_fee_diff)) + change_cost
+        add_coin(1 * COIN, 1, selection, fee, fee + large_fee_diff);
+        add_coin(2 * COIN, 2, selection, fee, fee + large_fee_diff);
+        selection.ComputeAndSetWaste(/*min_viable_change=*/0, change_cost, /*change_fee=*/0);
+        BOOST_CHECK_EQUAL(target_waste2, selection.GetWaste());
+    }
+}
+
+
+BOOST_AUTO_TEST_CASE(bump_fee_test)
+{
+    const CAmount fee{100};
+    const CAmount min_viable_change{200};
+    const CAmount change_cost{125};
+    const CAmount change_fee{35};
+    const CAmount fee_diff{40};
+    const CAmount target{2 * COIN};
+
+    {
+        SelectionResult selection{target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection, /*fee=*/fee, /*long_term_fee=*/fee + fee_diff);
+        add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
+        const std::vector<std::shared_ptr<COutput>> inputs = selection.GetShuffledInputVector();
+
+        for (size_t i = 0; i < inputs.size(); ++i) {
+            inputs[i]->ApplyBumpFee(20*(i+1));
+        }
+
+        selection.ComputeAndSetWaste(min_viable_change, change_cost, change_fee);
+        CAmount expected_waste = fee_diff * -2 + change_cost + /*bump_fees=*/60;
+        BOOST_CHECK_EQUAL(expected_waste, selection.GetWaste());
+
+        selection.SetBumpFeeDiscount(30);
+        selection.ComputeAndSetWaste(min_viable_change, change_cost, change_fee);
+        expected_waste = fee_diff * -2 + change_cost + /*bump_fees=*/60 - /*group_discount=*/30;
+        BOOST_CHECK_EQUAL(expected_waste, selection.GetWaste());
+    }
+
+    {
+        // Test with changeless transaction
+        //
+        // Bump fees and excess both contribute fully to the waste score,
+        // therefore, a bump fee group discount will not change the waste
+        // score as long as we do not create change in both instances.
+        CAmount changeless_target = 3 * COIN - 2 * fee - 100;
+        SelectionResult selection{changeless_target, SelectionAlgorithm::MANUAL};
+        add_coin(1 * COIN, 1, selection, /*fee=*/fee, /*long_term_fee=*/fee + fee_diff);
+        add_coin(2 * COIN, 2, selection, fee, fee + fee_diff);
+        const std::vector<std::shared_ptr<COutput>> inputs = selection.GetShuffledInputVector();
+
+        for (size_t i = 0; i < inputs.size(); ++i) {
+            inputs[i]->ApplyBumpFee(20*(i+1));
+        }
+
+        selection.ComputeAndSetWaste(min_viable_change, change_cost, change_fee);
+        CAmount expected_waste = fee_diff * -2 + /*bump_fees=*/60 + /*excess = 100 - bump_fees*/40;
+        BOOST_CHECK_EQUAL(expected_waste, selection.GetWaste());
+
+        selection.SetBumpFeeDiscount(30);
+        selection.ComputeAndSetWaste(min_viable_change, change_cost, change_fee);
+        expected_waste = fee_diff * -2 + /*bump_fees=*/60 - /*group_discount=*/30 + /*excess = 100 - bump_fees + group_discount*/70;
+        BOOST_CHECK_EQUAL(expected_waste, selection.GetWaste());
+    }
 }
 
 BOOST_AUTO_TEST_CASE(effective_value_test)
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index db04bb8bdb3ff..ed0d91c290245 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -315,6 +315,7 @@
     'wallet_sendall.py --descriptors',
     'wallet_create_tx.py --descriptors',
     'wallet_inactive_hdchains.py --legacy-wallet',
+    'wallet_spend_unconfirmed.py',
     'p2p_fingerprint.py',
     'feature_uacomment.py',
     'feature_init.py',
diff --git a/test/functional/wallet_spend_unconfirmed.py b/test/functional/wallet_spend_unconfirmed.py
new file mode 100755
index 0000000000000..bfcdeaeaa8995
--- /dev/null
+++ b/test/functional/wallet_spend_unconfirmed.py
@@ -0,0 +1,508 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+from decimal import Decimal, getcontext
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_greater_than_or_equal,
+    assert_equal,
+    find_vout_for_address,
+)
+
+class UnconfirmedInputTest(BitcoinTestFramework):
+    def add_options(self, parser):
+        self.add_wallet_options(parser)
+
+    def set_test_params(self):
+        getcontext().prec=9
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+
+    def setup_and_fund_wallet(self, walletname):
+        self.nodes[0].createwallet(walletname)
+        wallet = self.nodes[0].get_wallet_rpc(walletname)
+
+        self.def_wallet.sendtoaddress(address=wallet.getnewaddress(), amount=2)
+        self.generate(self.nodes[0], 1) # confirm funding tx
+        return wallet
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def calc_fee_rate(self, tx):
+        fee = Decimal(-1e8) * tx["fee"]
+        vsize = tx["decoded"]["vsize"]
+        return fee / vsize
+
+    def calc_set_fee_rate(self, txs):
+        fees = Decimal(-1e8) * sum([tx["fee"] for tx in txs]) # fee is negative!
+        vsizes = sum([tx["decoded"]["vsize"] for tx in txs])
+        return fees / vsizes
+
+    def assert_spends_only_parents(self, tx, parent_txids):
+        parent_checklist = parent_txids.copy()
+        number_inputs = len(tx["decoded"]["vin"])
+        assert_equal(number_inputs, len(parent_txids))
+        for i in range(number_inputs):
+            txid_of_input = tx["decoded"]["vin"][i]["txid"]
+            assert txid_of_input in parent_checklist
+            parent_checklist.remove(txid_of_input)
+
+    def assert_undershoots_target(self, tx):
+        resulting_fee_rate = self.calc_fee_rate(tx)
+        assert_greater_than_or_equal(self.target_fee_rate, resulting_fee_rate)
+
+    def assert_beats_target(self, tx):
+        resulting_fee_rate = self.calc_fee_rate(tx)
+        assert_greater_than_or_equal(resulting_fee_rate, self.target_fee_rate)
+
+    # Meta-Test: try feerate testing function on confirmed UTXO
+    def test_target_feerate_confirmed(self):
+        self.log.info("Start test feerate with confirmed input")
+        wallet = self.setup_and_fund_wallet("confirmed_wallet")
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.5, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_beats_target(ancestor_aware_tx)
+
+        wallet.unloadwallet()
+
+    # Spend unconfirmed UTXO from high-feerate parent
+    def test_target_feerate_unconfirmed_high(self):
+        self.log.info("Start test feerate with high feerate unconfirmed input")
+        wallet = self.setup_and_fund_wallet("unconfirmed_high_wallet")
+
+        # Send unconfirmed transaction with high feerate to testing wallet
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=3*self.target_fee_rate)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+        self.assert_beats_target(parent_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.5, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+
+        wallet.unloadwallet()
+
+    # Spend unconfirmed UTXO from low-feerate parent. Expect that parent gets
+    # bumped to target feerate.
+    def test_target_feerate_unconfirmed_low(self):
+        self.log.info("Start test feerate with low feerate unconfirmed input")
+        wallet = self.setup_and_fund_wallet("unconfirmed_low_wallet")
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=1)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(parent_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.5, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Spend UTXO with unconfirmed low feerate parent and grandparent
+    # txs. Expect that both ancestors get bumped to target feerate.
+    def test_chain_of_unconfirmed_low(self):
+        self.log.info("Start test with parent and grandparent tx")
+        wallet = self.setup_and_fund_wallet("unconfirmed_low_chain_wallet")
+
+        grandparent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.8, fee_rate=1)
+        gp_tx = wallet.gettransaction(txid=grandparent_txid, verbose=True)
+
+        self.assert_undershoots_target(gp_tx)
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.5, fee_rate=2)
+        p_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(p_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=1.3, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([gp_tx, p_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Spend unconfirmed UTXOs from two low feerate parent txs.
+    def test_two_low_feerate_unconfirmed_parents(self):
+        self.log.info("Start test with two unconfirmed parent txs")
+        wallet = self.setup_and_fund_wallet("two_parents_wallet")
+
+        # Add second UTXO to tested wallet
+        self.def_wallet.sendtoaddress(address=wallet.getnewaddress(), amount=2)
+        self.generate(self.nodes[0], 1) # confirm funding tx
+
+        parent_one_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.5, fee_rate=2)
+        p_one_tx = wallet.gettransaction(txid=parent_one_txid, verbose=True)
+        self.assert_undershoots_target(p_one_tx)
+
+        parent_two_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.5, fee_rate=1)
+        p_two_tx = wallet.gettransaction(txid=parent_two_txid, verbose=True)
+        self.assert_undershoots_target(p_two_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=2.8, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_one_txid, parent_two_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([p_one_tx, p_two_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Spend two unconfirmed inputs, one each from low and high feerate parents
+    def test_mixed_feerate_unconfirmed_parents(self):
+        self.log.info("Start test with two unconfirmed parent txs one of which has a higher feerate")
+        wallet = self.setup_and_fund_wallet("two_mixed_parents_wallet")
+
+        # Add second UTXO to tested wallet
+        self.def_wallet.sendtoaddress(address=wallet.getnewaddress(), amount=2)
+        self.generate(self.nodes[0], 1) # confirm funding tx
+
+        high_parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.5, fee_rate=self.target_fee_rate*2)
+        p_high_tx = wallet.gettransaction(txid=high_parent_txid, verbose=True)
+        # This time the parent is greater than the child
+        self.assert_beats_target(p_high_tx)
+
+        parent_low_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.5, fee_rate=1)
+        p_low_tx = wallet.gettransaction(txid=parent_low_txid, verbose=True)
+        # Other parent needs bump
+        self.assert_undershoots_target(p_low_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=2.8, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_low_txid, high_parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([p_high_tx, p_low_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+
+        resulting_bumped_ancestry_fee_rate = self.calc_set_fee_rate([p_low_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_bumped_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_bumped_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Spend from chain with high feerate grandparent and low feerate parent
+    def test_chain_of_high_low(self):
+        self.log.info("Start test with low parent and high grandparent tx")
+        wallet = self.setup_and_fund_wallet("high_low_chain_wallet")
+
+        grandparent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.8, fee_rate=self.target_fee_rate * 10)
+        gp_tx = wallet.gettransaction(txid=grandparent_txid, verbose=True)
+        # grandparent has higher feerate
+        self.assert_beats_target(gp_tx)
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.5, fee_rate=1)
+        # parent is low feerate
+        p_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+        self.assert_undershoots_target(p_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=1.3, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([p_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+        resulting_ancestry_fee_rate_with_high_feerate_gp = self.calc_set_fee_rate([gp_tx, p_tx, ancestor_aware_tx])
+        # Check that we bumped the parent without relying on the grandparent
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate_with_high_feerate_gp, self.target_fee_rate*1.1)
+
+        wallet.unloadwallet()
+
+    # Spend UTXO from chain of unconfirmed transactions with low feerate
+    # grandparent and even lower feerate parent
+    def test_chain_of_high_low_below_target_feerate(self):
+        self.log.info("Start test with low parent and higher low grandparent tx")
+        wallet = self.setup_and_fund_wallet("low_and_lower_chain_wallet")
+
+        grandparent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.8, fee_rate=5)
+        gp_tx = wallet.gettransaction(txid=grandparent_txid, verbose=True)
+
+        # grandparent has higher feerate, but below target
+        self.assert_undershoots_target(gp_tx)
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1.5, fee_rate=1)
+        p_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+        # parent even lower
+        self.assert_undershoots_target(p_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=1.3, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([gp_tx, p_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Test fee calculation when bumping while using subtract fee from output (SFFO)
+    def test_target_feerate_unconfirmed_low_sffo(self):
+        self.log.info("Start test feerate with low feerate unconfirmed input, while subtracting from output")
+        wallet = self.setup_and_fund_wallet("unconfirmed_low_wallet_sffo")
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=1)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(parent_tx)
+
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.5, fee_rate=self.target_fee_rate, subtractfeefromamount=True)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Test that parents of preset unconfirmed inputs get cpfp'ed
+    def test_preset_input_cpfp(self):
+        self.log.info("Start test with preset input from low feerate unconfirmed transaction")
+        wallet = self.setup_and_fund_wallet("preset_input")
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=1)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(parent_tx)
+
+        number_outputs = len(parent_tx["decoded"]["vout"])
+        assert_equal(number_outputs, 2)
+
+        # we don't care which of the two outputs we spent, they're both ours
+        ancestor_aware_txid = wallet.send(outputs=[{self.def_wallet.getnewaddress(): 0.5}], fee_rate=self.target_fee_rate, options={"add_inputs": True, "inputs": [{"txid": parent_txid, "vout": 0}]})["txid"]
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Test that RBFing a transaction with unconfirmed input gets the right feerate
+    def test_rbf_bumping(self):
+        self.log.info("Start test to rbf a transaction unconfirmed input to bump it")
+        wallet = self.setup_and_fund_wallet("bump")
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=1)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(parent_tx)
+
+        to_be_rbfed_ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.5, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=to_be_rbfed_ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        bumped_ancestor_aware_txid = wallet.bumpfee(txid=to_be_rbfed_ancestor_aware_txid, options={"fee_rate": self.target_fee_rate * 2} )["txid"]
+        bumped_ancestor_aware_tx = wallet.gettransaction(txid=bumped_ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        resulting_bumped_fee_rate = self.calc_fee_rate(bumped_ancestor_aware_tx)
+        assert_greater_than_or_equal(resulting_bumped_fee_rate, 2*self.target_fee_rate)
+        resulting_bumped_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, bumped_ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_bumped_ancestry_fee_rate, 2*self.target_fee_rate)
+        assert_greater_than_or_equal(2*self.target_fee_rate*1.01, resulting_bumped_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Test that transaction spending two UTXOs with overlapping ancestry does not bump shared ancestors twice
+    def test_target_feerate_unconfirmed_low_overlapping_ancestry(self):
+        self.log.info("Start test where two UTXOs have overlapping ancestry")
+        wallet = self.setup_and_fund_wallet("overlapping_ancestry_wallet")
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=1)
+        two_output_parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(two_output_parent_tx)
+
+        # spend both outputs from parent transaction
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=1.5, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid, parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([two_output_parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Test that new transaction ignores sibling transaction with low feerate
+    def test_sibling_tx_gets_ignored(self):
+        self.log.info("Start test where a low-fee sibling tx gets created and check that bumping ignores it")
+        wallet = self.setup_and_fund_wallet("ignore-sibling")
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=2)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(parent_tx)
+
+        # create sibling tx
+        sibling_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.9, fee_rate=1)
+        sibling_tx = wallet.gettransaction(txid=sibling_txid, verbose=True)
+        self.assert_undershoots_target(sibling_tx)
+
+        # spend both outputs from parent transaction
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.5, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Test that new transaction only pays for itself when high feerate sibling pays for parent
+    def test_sibling_tx_bumps_parent(self):
+        self.log.info("Start test where a high-fee sibling tx bumps the parent")
+        wallet = self.setup_and_fund_wallet("generous-sibling")
+
+        parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=1)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+        self.assert_undershoots_target(parent_tx)
+
+        # create sibling tx
+        sibling_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.9, fee_rate=3*self.target_fee_rate)
+        sibling_tx = wallet.gettransaction(txid=sibling_txid, verbose=True)
+        self.assert_beats_target(sibling_tx)
+
+        # spend both outputs from parent transaction
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=0.5, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        # Child is only paying for itself…
+        resulting_fee_rate = self.calc_fee_rate(ancestor_aware_tx)
+        assert_greater_than_or_equal(1.05 * self.target_fee_rate, resulting_fee_rate)
+        # …because sibling bumped to parent to ~50 s/vB, while our target is 30 s/vB
+        resulting_ancestry_fee_rate_sibling = self.calc_set_fee_rate([parent_tx, sibling_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate_sibling, self.target_fee_rate)
+        # and our resulting "ancestry feerate" is therefore BELOW target feerate
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(self.target_fee_rate, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+    # Spend a confirmed and an unconfirmed input at the same time
+    def test_confirmed_and_unconfirmed_parent(self):
+        self.log.info("Start test with one unconfirmed and one confirmed input")
+        wallet = self.setup_and_fund_wallet("confirmed_and_unconfirmed_wallet")
+        confirmed_parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=1, fee_rate=self.target_fee_rate)
+        self.generate(self.nodes[0], 1) # Wallet has two confirmed UTXOs of ~1BTC each
+        unconfirmed_parent_txid = wallet.sendtoaddress(address=wallet.getnewaddress(), amount=0.5, fee_rate=0.5*self.target_fee_rate)
+
+        # wallet has one confirmed UTXO of 1BTC and two unconfirmed UTXOs of ~0.5BTC each
+        ancestor_aware_txid = wallet.sendtoaddress(address=self.def_wallet.getnewaddress(), amount=1.4, fee_rate=self.target_fee_rate)
+        ancestor_aware_tx = wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+        self.assert_spends_only_parents(ancestor_aware_tx, [confirmed_parent_txid, unconfirmed_parent_txid])
+        resulting_fee_rate = self.calc_fee_rate(ancestor_aware_tx)
+        assert_greater_than_or_equal(resulting_fee_rate, self.target_fee_rate)
+
+        wallet.unloadwallet()
+
+    def test_external_input_unconfirmed_low(self):
+        self.log.info("Send funds to an external wallet then build tx that bumps parent by spending external input")
+        wallet = self.setup_and_fund_wallet("test_external_wallet")
+
+        external_address = self.def_wallet.getnewaddress()
+        address_info = self.def_wallet.getaddressinfo(external_address)
+        external_descriptor = address_info["desc"]
+        parent_txid = wallet.sendtoaddress(address=external_address, amount=1, fee_rate=1)
+        parent_tx = wallet.gettransaction(txid=parent_txid, verbose=True)
+
+        self.assert_undershoots_target(parent_tx)
+
+        spend_res = wallet.send(outputs=[{self.def_wallet.getnewaddress(): 0.5}], fee_rate=self.target_fee_rate, options={"inputs":[{"txid":parent_txid, "vout":find_vout_for_address(self.nodes[0], parent_txid, external_address)}], "solving_data":{"descriptors":[external_descriptor]}})
+        signed_psbt = self.def_wallet.walletprocesspsbt(spend_res["psbt"])
+        external_tx = self.def_wallet.finalizepsbt(signed_psbt["psbt"])
+        ancestor_aware_txid = self.def_wallet.sendrawtransaction(external_tx["hex"])
+
+        ancestor_aware_tx = self.def_wallet.gettransaction(txid=ancestor_aware_txid, verbose=True)
+
+        self.assert_spends_only_parents(ancestor_aware_tx, [parent_txid])
+
+        self.assert_beats_target(ancestor_aware_tx)
+        resulting_ancestry_fee_rate = self.calc_set_fee_rate([parent_tx, ancestor_aware_tx])
+        assert_greater_than_or_equal(resulting_ancestry_fee_rate, self.target_fee_rate)
+        assert_greater_than_or_equal(self.target_fee_rate*1.01, resulting_ancestry_fee_rate)
+
+        wallet.unloadwallet()
+
+
+    def run_test(self):
+        self.log.info("Starting UnconfirmedInputTest!")
+        self.target_fee_rate = 30
+        self.def_wallet  = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.generate(self.nodes[0], 110)
+
+        self.test_target_feerate_confirmed()
+
+        self.test_target_feerate_unconfirmed_high()
+
+        self.test_target_feerate_unconfirmed_low()
+
+        self.test_chain_of_unconfirmed_low()
+
+        self.test_two_low_feerate_unconfirmed_parents()
+
+        self.test_mixed_feerate_unconfirmed_parents()
+
+        self.test_chain_of_high_low()
+
+        self.test_chain_of_high_low_below_target_feerate()
+
+        self.test_target_feerate_unconfirmed_low_sffo()
+
+        self.test_preset_input_cpfp()
+
+        self.test_rbf_bumping()
+
+        self.test_target_feerate_unconfirmed_low_overlapping_ancestry()
+
+        self.test_sibling_tx_gets_ignored()
+
+        self.test_sibling_tx_bumps_parent()
+
+        self.test_confirmed_and_unconfirmed_parent()
+
+        self.test_external_input_unconfirmed_low()
+
+if __name__ == '__main__':
+    UnconfirmedInputTest().main()