Uploaded v1.04: I think I got the finale consistency thing working (including spells), and allowed you to start with items in Area 6 levels.
I decided I kind of had to force the girls to start with Unmake because of the limit break scene, but otherwise things should work as you'd expect. I modified 6-1 such that I'm pretty sure you can't just fall into 6-2 as the moms - you can bomb through the floor in some of the mom levels if you come in with 3 bombs, but at least you have to restart afterward, which will fix the characters. I also put up an invisible wall so you can't jump left from 6-2, as that area's possible to get over to now.