This topic actually brings up a question. Are you guys actually limiting the number of PCs people have in each group?
Like, say Angad, my mountain dwarf wizard here, gets to level 3 in this game. I decide I like her, and may bring her into another game eventually. In the meantime, I play one-shots with characters from other groups. Then a level-1 game comes along where I'd like to play another character from the same group as Angad, but she's level 3 now. Do I have to trash her to make a new Group C character, or can she stay in my stable of PCs?