Sibling cosleeping/room sharing

[lilysmama1124]

Just wondering at what age you would let sibs cosleep alone/room share. Here is the situation: I have a twon bedroom home, one large room and one small. Currently my 4 year old has her own bed and room where she was happily sleeping alone until she has recently wanted to cosleep again which we let her dictate so one of us is sleeping with her in there. We have a king size mattress on the floor in the big room as well as a lot of toys etc and a small twin futon mattress also on the floor. We put the twin one year olds on the futon mattress to start off the night and they crawl into bed with us at some to nurse and sleep. at the end of this room(it is long) we have a gate separating off what is supposed to be a small office area but what has now become a trash heap!!. The four year old has also been coming into sleep with the babies in the morning even if there is an adult in her room. What I want to do is make the small room and ADULT ONLY room. That way I can have an real office for my home based business and my husband can go for his home based business...also would like to move the tv in there to encourage my husband to stop playing video games in front of the kids but that is a different post. Then I could make the big room a family sleeping and playing room and just put all of the beds in there. My only concern is that the four year old can be really rough with the babies. I would only have toys in that room that are appropiate for all the kiddos so she would have to have her big girl toys in the dining room but that is already how we do it anyway. At what age did you trust you older sibling alone with the baby? It isn't like they would be alone very long but if they all woke up and we were asleep or if they were all napping and got up while I was down stairs etc... also I am afraid the oldest would open the gate and babies would get to the stairs but I could put a lock on the gate so she can't open it...that just feels weird to me though.