The stories about the daughters death amd the fake is mixed with the father. How can he tbink his daughter is dead when he's raising Katherine amd not know? A mistake was made in this story.
He was led to believe that the daughter was still-born and died at birth by the mistress who is a doctor I believe. So the ex-friend and mistress and him schemes to have their kid replace the "dead" child since the child is "dead" anyways.
This is not a light read for those with trauma. The development of the characters was somehow else altogether though. Wow, what a story.