It's difficult to balance your family and your in-laws. I've been married a long time, some of my husband's family are like actual siblings to me, and others are just like strangers that happen to be my husband's sisters/father.

I wish I had a good answer for you. I try to be a good hostess, but I run out of things to say and find myself gravitating to those people that I am closer to. My husband and I have been together for almost 30 years. And after all of that time this is what we've come up with: we invite/attend these functions for the sake of our children. We go into it knowing that we do not enjoy spending time with certain family members under certain circumstances so as guests we focus on spending time with those people that we do enjoy. My husband doesn't always get along with my brother, so I make sure that I entertain him when he's here. I don't like one of his sisters (he doesn't like her either) but it's his sister to it's his responsibility to entertain her when she comes. And my favorite Aunt (whom I love dearly) is opinionated and preachy so I try to keep her away from hubby's family by keeping her occupied myself. Family politics are so complicated.

For example, I have a SIL that I do not like. We do not mesh, I cannot have a conversation with the woman without being offended and insulted. But I love her children dearly and would not dream of missing an event because of this. So when we go to her home we greet her, spend some times with the kids (who are now in their late teens and 20s) so when the Auntie/Uncle time runs thin we spend time with the other relatives that we do enjoy. And we also put a time limit on how long we are going to stay. Either we arrive after dinner or leave before it's served. Please don't let your SILs behavior keep you from the important milestones of family life.