My SIL wants us to go in on a joint birthday party for my DN (4) and my DD (3). Their birthdays are a day apart. We may plan a small kid activity on DDs actual birthday, but are ok with a joint family party on the weekend. The problem is that SIL will also be inviting DN's friends so that it will be a kid plus family party. She is planning Batman inspired invitations. Personally, I don't care too much about the theme, but am stumped as to how to word the invite so that family knows this party is to celebrate both their birthdays, but SILs friends don't come with gifts for DD. Any one have experience with joint parties....do you do seperate themes? Separate invitations? Separate cakes? Any advice would be appreciated. TIA