I ended up just making a simple macro that set the master for each toon:

/jamba-team master riffz
/run DEFAULT_CHAT_FRAME:AddMessage("Master set to RiffZ");

And a similar one that set their master back to whichever one was appropriate for each toon. The teams already have all of the JC's and their normal composition so whoever is online is who gets invited. Simple solution.

I just didn't know about the slash commands.. nifty.