Telling them early is when they feel guilty but ya she should have told them
She promised the original one to never let them know their daughter was already dead. Feng Jiu was simply loyaly adhering to the conditions she was given.
Bigger question is; How did these unknown assailants know that the original was already dead? She killed the man trying to assault her back then and there was no one else.
Though they could just be trying to stir up discord within the family of course.
This is why she should've told them earlier. If this is a repeat of that manhwa, I gonna...