What do they want?

ETA: ok, re-read your post. Hard to know what they'll want in 12-24 months time. But that's how I'm planning things anyway. There will be three beds. I don't really mind which one they sleep in or in what room. I just want them to sleep, get along as best they can and feel happy that what they want in terms of space, belongings etc is respected. I don't think it has to come down to age or gender... just about individual personalities and needs.