I put 8 week old chicks in segregaton/integration grow out coops/pens within the run. I put up a temporary fence with garden stakes so the youngsters have a small run area of their own, with their feeder and waterer. They stay there for about 2 weeks to a month, depending on their size.
The main flock gets to see and hear them, do some posturing and pecking through the fence but not hurt anybody. Chest bumps through the fence, and the like. By the time I take down the temp fence, the older birds already know who the younger ones are, and the pecking order issues are very mild. There's some chasing, some pecking, but it's more to let the youngsters know the Original Flock is higher in status and get first dibs at the feeders, waterers and any treats.
This has worked for me SEVERAL times. If you don't have a separate coop, a dog house or something similar can work for the short term.
Good luck and may your integration issues be minor!