what would you do?

so back story is my oldest daughter doesnt live with me instead she lives with my dads ex whom is her guardian until i get my own place .. so anyways we were at a birthday party and all the kids were playing well my daughter ignored her step brother which made him so upset he jumped at her causing her to fall and almost hit a bookshelf.. right then they heard us all sing happy birthday none of her siblings asked if she was ok or helped her.. when we spoke to the boy he shut down like literally just blankly stared at us when we asked why he would do that.. so when i went to drop off my daughter her grandmother said she is no longer allowed to be around the boys unless me or my husband are present in the same room... i vented to my dad who said my stepmom has control issues which she clearly does but my husband doesnt agree that we should be watching these kids every move because regardless if we were present or not kids are going to dight and play around ... it is currently putting a wedge between us.. idk what to do.. do i let her play with her siblings alone or sit in while they play .. their ages are 11,10,10,8,4,2  and 8 wks... if it helps any his two boys lack respect towards me and give me soo much attitude when i ask them to do something... my husband sees nothing wrong as he just talks to them but nothing changes