The daughter has a right to decide not to have anything to do with new wife. That may mean losing her relationship with her father, but it is her right. Obviously the daughter is not past the "adjustment period" in her mind and no one is going to be able to force the issue. If her father attempts to have a "serious talk" with her, he may find himself on the receiving end of an ultimatim. Much like the one I delivered to my mom when she attempted to get me to call her new husband "dad." I told her, "I'm happy for you that you found someone that makes you happy. I'm a grown man and I don't need a dad. I will continue to refer to him as 'my mom's husband.' If you or he find this to be unacceptable, you will need to decide what you will do about it." (Nothing happened.)

At any rate, the daughter wasn't the rude one. The new wife is the rude one for showing up where she knows she's not welcome, bringing someone else she knows is not welcome, and thinking that her presence should be accepted. (Not to mention she's a cruel witch for putting her challenged son through that in the hope of gaining sympathy from the daughter.)