I bought some chicks (3) at a sale so I don't know how old they are. I know I still can't distinguish the pullets from a cockerels yet. Anyway they look to have some RIR in them if that makes a difference. I have been keeping them in thier own cage but don't like it. I just don't want them to get hurt or lost.
I agree with katrinag that you should keep them separate for at least a month to make sure no one has any illness or such. Then, if they are the same size as your others you can integrate them together. If you are going to have them together in the coop at night or locked up at all in a run then if they are smaller you really want to wait until they are the same size. If you are just going to have them out at the same time when they are all free ranging you probably can put them together sooner. With the extra space the little ones should be able to get away from the older ones if there are squabbles.
How big were they at six weeks? Mine have all thier feathers and and look to be half grown, but I'm a newbie and have no idea.
I let my 2 EE chicks free range with my hens and rooster at 11 weeks old. They pretty much avoid the adults but they still react to the adults cries of danger.
