I liked the idea of Aeris as the bad guy, I also think it would open up Sephiroth to be the good guy he could have been had he not been a puppet to Jenova.

Three problems:

I'm almost certain Cloud was an only child.

How can Reeve AND Cait Sim be in the same party?

Marlene getting cast out seemed a bit out of FFVII style to me, as did Reeve trying to throw her in a swamp. That definately felt FFVIish I thought.