G.G.
If you send the invites to their homes rather than give them out in class, I see no reason you can't limit the guest list. I know it's the politically correct thing to do to invite each child, but I think it's too much. Not every kid wants to attend each party, it's too expensive for the hosts and for the guests who have to bring 20-30 gifs throughout the year. I would ask your son not to discuss the party at school so those who are not invited don't feel left out.