Splitting twins into their own bedrooms - one is desperate for own room, the other terrified

[warmbath]

Help! DT are both 11 (girls). They have shared a bedroom since birth. They get on well most of the time as siblings are and are popular at school with lots of nice friends.
DT1 wants to move into her own bedroom as wants her own space and friends over to hang out and sleepovers.
DT2 is like me as a child, she is afraid of the dark and doesn't like sleeping alone in a bedroom. She would also benefit from having her own space to have friends over and sleepovers.
I really don't want to have to sleep in her bedroom at night to keep her company, I'm too old for that now (I have two older teenagers).
Anyone got some wisdom, would be much appreciated!

She is literally terrified of being alone I. Her bedroom at night...

Is she able to articulate what it is that she's scared of?

Just that she doesn't like being alone. I was the same when I was that age, in fact felt like this til I was married despite living alone in London in my own flat for a couple of years

Could you have another bedroom for the daughter who wants her own space but ask that she still goes to sleep in the other daughter’s room? She can still have a place for herself and her friends to go round but when she’s ready to sleep goes back into the room? And that way it could be a smoother transition as well, the daughter that is scared could slowly get use to her being there less and less. When one is having a sleepover the other could too in their own rooms.