1 - The player's original dimension, where we always beated the guys in the espansions because we don't suck. The Allies win the war, we defeated Promathia, life is good.
2 - Lilith's alternate reality, the world of strife. According to her it was the first dimension of reality where the Allies lost the Crystal War. But Altana was so bummed she just made up our dimension instead where the Allies won. In Lilith's world however the allied races of light resort to forging a pact with Odin to survive and continue endlessly battling the Beastmen races. They "survive" but at the expense of selling out to Odin and living in constant strife. In this world the Shadowlord presumably isn't killed, hence the noise in the crystal line remains, hence the zilart princes never enact the plot of Rise of the Zilart. Which come to think of that, wouldn't that also imply the events of CoP couldn't unfold also?
3 - The Abyssea dimension that slit off in a reality where the player lost his fight with Promathia in CoP. Promathia then absorbed Selhteus and became more powerful and also a dragony thing. The mothercrystals left the crags (presumably destroying them since they're gone). They take position around the capital Altieau which fell to the moon. The few survivors struggle to fight against an onslaught of monsters.