It wasn't me, but my parents who went through this... when my baby bro was born (he's 7 now, growing up!) they contemplated putting him in with my other bro (who was 8 at the time), but it just didn't work... When my baby bro was sleeping my other bro couldn't go play in his room just in case he woke him up, and couldn't have his friends over... it didn't work for very long at all! But we didn't have a spare room so my baby bro slept in mum and dads room til he was about 2 and then they had to share, but it was less of an issue with him being a bit older.

Hope you work it out!