What should I do about this?

I’ve only posted anonymous because I don’t know if this person can see what I post my brother has recently started dating a young lady after three months of knowing each other they got pregnant after nine months of knowing each other got engaged which is fine because I always say move at the pace that feels great for you my problem is she didn’t grow up with any siblings and I can understand that but with the baby and my brother if feels like she’s trying to keep them separate from the family and it’s four of us we grow up very close we are literally one year and three months apart all four of us so we grew up very very close it just feels different now that my brother has been dating her and honestly i really don’t like her her mom also wasn’t really active in her life growing up and her dad was sort of just the type of father that pays child support and they both let her grandmother raise her so I can sympathize with her not having a family dynamic like we did but my brother has been so frustrated lately and venting to me and I kind of hate that he did that because I already didn’t like her and now that he has been confirming how she’s trying to keep the baby from us and keep telling him that he needs to worry about his family that he created only and my brother has been good to her from what I understand as far as paying bills being there for her needs helping out with the baby going to every doctors appointment going back-and-forth to the airport every time her mom come visit picking her mom up my frustration is that she for some reason doesn’t like our mom because our mom is a very needy mom I will admit that and my spouse doesn’t really care about it and neither does my other brothers wife she purposely wants to just separate my brother from the family and it really frustrates him and it also frustrates all of us but I’ve been trying to be nice to her because I don’t wanna have no family drama