NC because I just think I should.
I went out for dinner with my mum and three aunts the other day. Two of my aunts have a on off good/not so good relationship with my grandmother and my mum and another sister are on very good terms with her. My grandmother was treated very poorly by my grandad. My mum and other aunt were asking two other aunts how it has come about that they are closer to their dad than their mum given how badly everyone knows he treated his wife. My mum and other aunt can take or leave grandad (I feel similarly, but I am kind to him out of respect, but we are not close).
If this is your situation how do you explain it? I know everyone's story is different, but I have seen this in other families too. It seems to go something like 'I know my dad treated my mum badly, but he was a good dad to me, so i see it as nothing to do with me'. Or as one of my aunts put it, she blames my gran in a way for staying with my grandad for so long and putting them all through it, but he was a good dad, so again she separates that.
It wasn't a tense conversation, all the sisters just talked it through, but we all had questions at the end of a thoughtful chat.