Responses
If you're talking about when the fake took over her body he noticed immediately something was off he tried to work through it, but felt like it wasn't his child. It's in chapter 77 & 78
Chapter 77~79 for the father learns everything and you learn it too
the grandfather was around those chapters, but doesn't understand why she went this way
When did he notice the difference? And when do they all realize what actually happened to her and her mother when she was a child?