Does anybody know whether the HP Retraining rules can be applied to your companion, familiar, or eidolon? Thank you in advance.
Strictly speaking probably not (a change from my previous answer), but I can't see a real reason why a GM would prohibit it if you can justify why the (e.g.) monastary undertook the training.
PFS says no, but their sole reason is that ACs don't have prestige to spend on retraining (a requirement in PFS). I know they are talking about changing it though.