Birthday invite etiquette for sports teams?

[oceanbaby]

My son is starting Little League, and his birthda is in a few months. He wanted to have it at a gymnastics place, so I have to make reservations now (the place fills up fast). The time I pick is based on the number of kids we can invite.

Is a sports team like a classroom, in that it's okay to only invite a few kids as long as you invite them privately? Or is it more close knit, and is it more appropriate to invite the whole team (9-10 kids)?

This is our first team experience, so I could use some help.

[limabean]

I would think classroom etiquette rules would apply -- as long as you hand out the invitations privately rather than at a group event, it's fine to invite just a few teammates.