How old will the chicks be when you let them out to free range? If you are brooding them, where is the brooder and can the adults see them while they are in the brooder? A better idea of what you are working with could help.
My brooder is in the coop. The chicks go there straight from the incubator or post office so the chicks are essentially raised with the flock. At five weeks I open the brooder door and integration is over. I have a relatively large coop for the number of chickens I have, over 3,000 square feet of room outside, and weather they can be outside all day every day. I have several widely scattered feeding and watering stations.
What do you consider trouble? You never know what will happen with living animals but usually with true "free range" room and just a few basics it's usually not a problem as far as the older ones trying to kill the younger. It can happen, you don't get guarantees.
keep them in a separate area of our barn to roost , nest, and feed.
This is where it could be fun. If you keep them locked in that other area in the barn for a while they will probably return there to sleep, at least initially. Eventually some or all may move in with the adults to sleep, but probably not for a while. Or they may always sleep apart. Any group could eat anywhere if they have access. Your young pullets might lay in the nests where you are trying to keep them or they may lay where the older hens are laying. Once you let them out where they all have access to everything you have lost control. They are going to do what they want to do, both young and old.
