I'm sure if the North Mexicans ask nicely, they could be incorporated as a 4th territory. Not 11th province though, they're not exactly shown to be responsible enough for that amount of privilege.
(Is it too late to expel them from future international events, or do we have to wait for them to actually invade someone? Not much sense in singing kumbaya in any tournament with a country that wants 1 or more of the other participants destroyed.)