Just want some advice.
My MIL (Memaw) has had lunch since before I was married to Mikey. Its always been around 1, depending on the game. My SIL's Mom has always had a dinner for her family. So SIL and family would come over to Memaw's house for lunch, then to her parents house for dinner. This year her Mom decided to have lunch

My SIL will not come eat lunch with us, she is going to her moms house. Memaw is OK with that, however SIL wants to take her DH and kids with her. I understand this, family day. Memaw is not OK with her son not being here. She wants him to come to her house, while his wife and kids go to her parents house. Memaw and the other MIL have never gotten along, I have to admit the other lady is hard to get along with, I have know them as long as I can remember.
I don't want to take sides with either side, I want to make peace. Is there anyways to make this blow over? So that our lunch is not full of anger?