I have a 6 year old daughter and a newborn. Both are from different relationships. My older daughter has started to say the baby isn’t her sister which is odd since she has always called her “baby sister.” The only person I have heard say they’re not related is her father. My entire family has suspected he is putting ideas into my daughter’s head since he and his family are extremely close minded. I spoke to my daughter already and explained they are sisters and she started crying saying “we have different fathers that’s why we are not sisters.” I already spoke to her dad (this is not the first time) to stop speaking to my daughter about adult issues but obviously he does not understand and keeps doing it. I don’t know what to do anymore