WWYD?

Okay, including my stepdaughter, we have 3 girls and 2 bedrooms.  Currently, DD1 and DD2 share a room.  They very rarely wake each other up in the middle of the night and I think they like sharing a room.  SD has a room to herself.  She doesn't get along well with DD1 and I know DD1 would go through all of her stuff (SD is 11 and we have her every other weekend and half the summer).  SD currently gets along with DD2 but I know that will change as DD2 gets a bit older. My problem is that I am trying to start earlier bedtimes for DD1 and DD2.  DD1 is generally in bed by 9 but is starting to stay up later and later and is grouchy the next day so I am trying to make bedtime a priority.  DD2 is generally in bed by 10 but that really varies.  DD1 goes to bed first because she can not be quiet while she is laying awake.  DD2 goes down drowsy but awake, makes a few little noises and goes to sleep.  If DD2 is in bed first and DD1 is ready to go to bed, it's fine, DD1 will stay quiet enough.  But if DD1 is in bed and I try to put DD2 down, DD1 will talk and I will have to take DD2 back downstairs and start over trying to get her to drowsy.  I am thinking about moving SD in with DD2 and letting DD1 have her own room.  I don't know if this is an extreme measure though.  I will have to deal with keeping the girls out of her stuff (right now when she is not here, we close her bedroom door and out of sight, out of mind), not to mention that I don't think DD1 will like having her own room (but she doesn't respond to the 'if you dont stay quiet, Im moving you' threat).  Do I go ahead and move them or do I just suck it up and try to continue coordinating bedtimes, just earlier?  It's really only maybe 3-5 times a month where DD1 causes problems but I'm thinking with an earlier bedtime, it's going to become more frequent (tonight for example, she was in bed by 7:30 and stayed awake until 9:30 when I tried to put DD2 to bed.  She finally passed out on the couch about 10 minutes ago (10:40)).