Splitting bedroom in 2 multiple children

[MummaL32]

We are in a 3 bedroom house with 5 kids (4 boys). Eldest (girl) teen has smallest bedroom which is fine. Three other boys have a shared room. (Stepson stays half a week so half the week it's two sharing a room and the other half is 3, all the same age all 8-9 it's a pretty good size bedroom 5th child is almost 2 still sharing with us! He is the reason for wanting to divide , (he is a terrible sleeper and feel both me and DH and baby will all sleep better (I hope)

Has anyone do this with multiple children?
I was thinking of splitting the boys bedroom so the three stay togerher Altho make there space slightly smaller and divide the bedroom for baby to go in, trouble is it only has one window in the room centre I would prefer to try and sound proof it as much as poss as 3 boys calming down of a night isn't quiet so I would need something up to block some of there racket out,
We want to extend but still a few years off that currently so want to try make most of what we have till then ,

So how does it work with the window does there have to be a gap between the stud wall and grass? (Sorry if that sounds stupid)

Do I need to buy two doors?

If anyone has done anything remotely similar please share

Thank you 💕

Would it be easier for you to sleep downstairs, put the little one in the smallest bedroom, the boys in the largest room and the teen in the other room, if you are planning to extend in the near future?

Could you divide yours and DH room instead for the baby ?

If 3 boys already sharing making the room smaller might not be possible and the window is an issue I’d think. You would have to move the window across or make it smaller, then put another window in for the divided part surely?

It’s hard to know re room sizes and house layout?

If you post a diagram we might be able to offer some more suggestions.