Also to clarify, one of our girls is just the type who needs space and is very demanding in general. The other is not, she's very friendly and hardly understands or respects her sister's boundaries. Ideally the girl who needs space would have her own room, but I think it's important that they both learn to live with other people. Is this something they might just outgrow if I find a temporary solution (like having one of them sleep in the boy's room), or is this something I need to help them learn from a young age? I'm very into just giving the kids space to be themselves and not forcing chinuch on them. But maybe it's not in their best interest to bend over backwards to find a solution?
She's already stretching herself to share a room. I would accommodate within that as much as possible, by not having the beds that close. I don't think there's any chinuch in repeatedly placing her in circumstances that are very trying for her personally.