DS1 got a birthday invite from a classmate today. The envelope didn't have any names on it specifying who it was for. Am I to assume my family of four is invited? Just LO? LO and only one parent?

Fwiw it's a two hour party with pizza and cake at a local children's museum. I'll probably have to end up asking, but didn't know if it's something most people automatically know and I'm just clueless lol.