AFAIK, there is no group limits. I think i grasp the problem here, but what would be really good is if you let me take a look at your groups.
If you can meet us on irc.freenode.net Im sure I or one of the other Tikians can sort you out. The channel is #tikiwiki
If you would like message me some details I will login myself and look at the groups, see whats happening.