Question about Community Invitations

My co-leader and I are each running communities. (She created both of hers.) I have 199 invitations for the Young Wizards community, and zero for The Tomorrow People community. She has 199 invitations for her personal blog. If we use some of those 398 invitations for people wanting to join The Tomorrow People is that going to cause problems? Or will they end up auto-joining the other two communites? Thanks!