Confederating ennemies

Hello, I am 30 turns into a dwarf mortal empires campaign as grombrindal. I know condeferation is more difficult than in the first game, and that the only way to achieve one easily is to wait for the IA to lose all its big stacks at once. considering that karak azul has 6 settlements, is number 5 world power and is only in one war with a one settlement orc faction, it is not going to happen anytime soon by itself, especially if I mop up their orc neighbors and surround their settlements with mine.

My question is : is it possible to confederate factions of the same race as yours you are at war with ? If it is the case, could I just blitzkrieg their armies in one or two turns and confederate them for free just after ?