It does sound very complicated. I don't see how it can work in the long run? I would either look at saving to add on and convert a garage, attic, basement, or porch space to a bedroom or at buying a different house and/or figure out another way to get the children enough privacy but not so they are living in their bedrooms; bedrooms are for sleeping.

I would make them their own storage or sitting/study areas and see if I could spend more time with each, alone. If I had a walk-in closet or something I'd convert that to the oldest girl's space, only she would be allowed in there with her clothes/stuff/perhaps desk to do homework, etc. and try to neutralize shared bedrooms so no one cared a lot since they would just be for sleeping, have a bed and dresser perhaps.