Who should be able to go?

My ex husband and I do 50/50 custody. My daughter has a school event this Friday and we all planned to go (him, me and his wife) the school just announced they will only be letting 2 adults in per child.

My ex husband is going no matter what because it’s his week with our daughter…but does this mean his wife should be able to go or would this be something you let bio mom (me) go to?

I really would hate to miss but I’m trying to side both sides and be fair. Honest opinions