so I'm hoping that DW's aunt is successful in getting him to at least give us some courtesy, even if he doesn't actually want to. She told me privately that if he fails to at least treat us in a friendly manner that she has no qualms about telling him he's unwelcome at family gatherings that we attend.
I don't know if you listen to Dan Savage's podcast, but he's pointed out on SEVERAL occasions that the acceptance of our families has become much more common place, and that it's the people who still discriminate against us who will be ejected from family gatherings, not us queers and our spouses and offspring. It's not drama-causing, he's doing a lot of this all by himself. Replace sexuality with skin colour, religion, country of origin and work it through your head. Would he reject you and your daughter if she were mixed race, or if you were a different religion than him? If the answer is no, you guys have some serious pondering to do. If you talk to DW's family and they all make you welcome and won't put up with his shit, then EVERYONE needs to put their foot down and tell him to change his attitude or he's not welcome.
The podcast I listened to the other day actually underlined this multiple times. The time for us to feel apologetic for being who we are (the "oh, well I've come out and that's enough drama in the family and I'm just going to let people walk all over me because I feel guilty for putting my family through my coming out") is over. You and DW have *nothing* to be sorry for, you have a wonderful daughter and are raising her to be a respectable citizen of this planet. Queer parents as a whole are better parents than non-queer parents, simply because we have to put so much energy into our family-rearing. Chin up! You have ever right to be at Christmas dinner and to be treated with respect (the whole "oh, just ignore him, he's old" excuse is bullshit and you need to squash that. It's another excuse for hateful, bigoted behaviour.)
Your family is awesome sauce, just like the rest of your kinspeople. The flip side is that if DD starts to realize how terrible it feels to be left out, she may reconsider doing hurtful things to others down the line.
Annd uhh... sorry for the rant, but this kind of situation bugs the snot out of me (although I'm sure it bugs you more!!).