i think if it were me i would stay, because i only have DD as well, so i would just pay for her and let her play. but i know it would be harder if you have more kids. but i think as long as you pay for the other children it's generally not a problem. it might be an opportunity for you to get to know DS's friends mum if they're going to remain friends?

LOL @ your son being more excited that this party than his, it's so typical isn't it?