Hi! I had to unscreen this so you'd be able to see my response, but I'll screen this again if you'd like. Basically the current reason things are set up the way they are now is because of how quickly casts can pile up in a game that allows multiple versions to exist at once. Taking the Homestuck cast as an easy example, there are twelve main kid trolls in the canon. Allowing one set of alternates means there are twenty-four, and allowing yet another alternate set means a potential for thirty-six characters--and of course there are more than just the trolls in Homestuck, so casts can grow massive very quickly here. The other option I considered was putting a limit on the amount of characters per canon, but I'm not sure if that would really be a better solution (though I will discuss it with the others).