How big is your coop...in feet by feet?
I integrated the new chicks into the flock at 4 weeks old this year, was the easiest integration ever.
Had them in the coop at 1 week old, separated from the main flock by a wire wall.
My coop is 6 x 16, the wire wall separates off 4 feet of that for the chicks, and there's a separate run for them too.
The main run is 8 x 50, the smaller run is 8x12.
When the chicks were 4 weeks old I opened the 3 tiny doors in that wall and the chicks went in and out those doors and mingled with the adult birds.
There was some pecking and chasing but no real problems at all, chicks were too fast to catch and the adults can't get thru the tiny doors.
The chicks had their own food and water and couldn't reach the adult feed/water anyway.
At 6 weeks I took the wall down completely, integration complete.