I'd help her. My husbands ex and I are good friends, so are my ex and I. We all have holiday dinners together. I know it sounds strange but it sure makes life a lot easier on the kids. I remember about 8 years ago when we had dinner with my husbands ex and all our children. His oldest said it was really nice to be able to have the holidays with both parents. I wasn't really crazy about the idea at the time but when his daughter said that it made me realize who really does pay the price when the parents divorce. My ex is also remarried, his new wife is very nice.
We had a court hearing to get custody of a granddaughter (1 1/2 at the time) who was living in a very bad situation with her mother and stepfather. My husband's ex came to court and testified for us. We got custody and the judge said this was the best, well adjusted family he's ever seen in his court. He said he felt we all had the children's best interests. Made me feel good to hear that from a judge. I've never said a bad word to my children about their father, I don't need to, they were there and know what happened.
So, based on our situation, help her. I know it's for him, but it's her gift to him. And believe me, in the long run it will be your gift to your daughter.