I just acquired 2-14 week old pullets and 1-14 week old cockerel, I set up a seperate area for them in the run and already had a built-in brooder in the coop. They were delivered at 8am and went straight in the separate run area. I watched and only the lowest in the pecking order paid any attention to them, and after talking to the person I got them from (who suggested I just let them out and see what happened) I released them 5 hrs after I got them. There was some chasing and pecking and everyone wanted to get a look at these new folks, but no blood shed so I left it be. That night I put them in the coop and they went to bed. The next morning was the same as the day before but less intense and they put themselves to bed. By the fifth day everything was as if they were there the whole time and are now at the bottom of the pecking order, but everyone co-mingles and resects everyone else's space. This Sunday will be 3 weeks. I agree with
@3KillerBs if there's no blood shed let it play out, supervised of course.