And to all that, I say:
Blah!
Anyway, the P12 alliance thing isn't really surprising, but what I found is that different buildings owned by different players (with different alliance settings), given to P12, will inherit their previous player's alliances, even if those alliances are changed later on (while still belonging to P12.) I find that interesting, because it shows a bit more is going on than meets the eye.
Also, and I'll try to post a sample of it later, in my Minesweeper map, if someone leaves the game, all their marked squares (which belong to P8: a permenant computer player) automatically switch ownership to P1, or at least, the lowest numbering player in the game. It's been a while since I've gone over the triggers for that game, but I'm pretty sure there wasn't anything of my creation that was causing that. The only way I could solve that problem was to use a failsafe to manually give the marked squares (factories) back to P8 after a player left, but to this day I never really figured out what was going on there.