Hmmm....I'd like MCVs to have defenses. Can a structure have 2 turrets, out of interest? I would like to make the MCVs have their own sentry gun/pill box and flak cannon/patriot, and have a small amount of power. That would be nice anyway.
So is it possible, and could anyone edit the Soviet and Allied SHPs and fit in the weaponry?
No you can't have 2 turrets.
But you can specify 2 firing locations for the 2 weapons.
But the turret will always turn toward what the building is firing at no matter which weapon is being used.