suffices Ghf: h f \in G by rewrite -Dh1 ?Ghf ?Ff /=.
by apply/group_prod=> i Pi; rewrite (subsetP (sAG Pi)) ?Af.End MorphIsometry.Local Notation G := <<B>>.
Local Notation H := <<A>>.cfInd_subproof phi : is_class_fun G (ffun_cfInd phi).
Proof.

(* Specifications: *)
case: subsetP => [sHG | _]; last by