My kids are young and their birthdays are exactly 3 years and 1 day apart. We have their birthday parties together for now because they are still young (turning 4 and 7) they also get along and don’t mind at all sharing a birthday party.

When making invitations should I put that it’s a joint birthday party? I don’t want parents to feel obligated to get something for both kids but I also don’t want them to feel bad that they didn’t know and didn’t get something for the other kid. How should I word the invitations?