Mom's 90th birthday is a special occasion. It might be awkward for everyone for Mom's son to bring a passel of family members to her birthday party. On the other hand, it would give his daughter an opportunity to meet her extended biological family, and for them to start establishing a relationship with her and her adoptive family. But ultimately I'm with elizabethann - Mom's party is about Mom. So yes, ask her how she feels, and since it is his daughter, he should be the one to host an event for her and her adoptive family. Elizabethann, you are so sweet to offer to have an event for her on top of everything you are doing to get ready for Mom's birthday! I hope it all works out (((HUGS)))).