Shared bdays

Yes to all of the above. If the 6 year old invites kids that only know them, I’d think that person would get just the 6 year old presents. If family friends who know them both came, I would anticipate either a joint gift OR a gift for each individually, both are right answers. But truthfully I typically say ‘gifts not necessary’ because presence is more important than presents and my kids have a ton. Especially when the birthday is near Christmas. My kids have too much already.

I know someone who did this and guests handled the gifts differently. Some brought for one (eg the friend in the kids class) some for both. Just prep the kids to expect to share some if the gifts and go in with no expectations.