[@King Kindred] Well, on the Am and Karre front, would it be ok to go with the Garland backstory in this way:

Garland is who Xehanort worked with back in the day to perfect the Nobody creation technique, then they went their separate ways. Garland has created Am and Karre as his Angels of Death, and much like in FFIX, during their first story, Am ends up killing the old man in frustration of his attempts to limit her power. After Am kills Garland and Terra, she throws her lot in with whoever seems more story appropriate at any given point. Maybe one of the Villains of the World, maybe Xehanort, maybe Maleficent, maybe the Organization. At this point, her only goal is to get Karre back on her side so they can spread war together, just like dear old daddy wanted.

The important thing is that Garland doesn't survive long enough to muddy the waters of the story, he's simply "The mad genius who was the first to perfect the Nobody creation technique. He had his own plans to save his world, but dies before he can go through with it and instead, Xehanort made off like a bandit with his notebook on how to do it." Sort of like Ivo Shandor in Ghostbusters. 

This is assuming that Xehanort is still behind the Organization in this game. If not, replace Xehanort with whoever. But in any case, a Final Fantasy character has an important role in the story, but it's more of a foot-note rather than another whole long and messy storyline we need to worry about.

If it's still a no, i'll shut up about Garland and move on.