We kept our pullets separate form our older girls for the first week. We had them in a fenced off area in the run so they could still see each other. After letting them out during the day together for a few days, in the middle of the night when the other chickens are in bed, take all the pullets and put them with the older ones. This way they'll be confused and when they all get up in the morning they might just think they were there the whole time. This will just keep the pecking order a little less violent but it doesn't mean it will stop it. They have to develop there pecking order no matter what. It seems like your birds may be getting along fine already but hope this helps a little anyways!
