Scenario 1)
Id try my best to end the war with the superior country, in a way that benefits me, such as giving it what it wants, and allying with it, after that I'd use his resources to attack country B, A and the superior force would join me in this, as I take down B, I'd then capture then sabatoge power plants, electrical dams, etc in the superior country. While making it look like country A did it, after that, with the superio countries forces dwindled and the populace sick of war, I'd invade while it is busy with country A, taking over The superior forces country, soldiers and weapons.