I think the problem is that ``final_electron_collection`` is the item at the tail of customizeElectronSequence, not the sequence it self.  I think what you want to do is use the if to "insert" them into the cms.Sequence.  i.e. add 

```python
if kwargs['eleReg']:
   process.customizeElectronSequence.insert(0, process.calibratedPatElectrons)
   process.customizeElectronSequence.insert(0, process.eleRegressionEnergy)
   # NB the order, as we are appending to front

This has to be before we paste the input electron collection, ``selectedPatElectrons`` into the start of the chain, @
https://github.com/dabelknap/FinalStateAnalysis/blob/397fed449e49047f3bae9530c98f04f391ea0e34/PatTools/python/patTupleProduction.py#L330

Does it make sense?