You will want to supervise for the first few times to see how it goes, there could be trouble or it could go easy. The more room and places to hide and escape will make things easier. Be ready to separate if things get rough, than try again the next day until everyone mostly ignores each other and there isn't excessive pecking. Having things the young chicks can slip under or through that the bigger ones can't, can give the younger ones a place to be safe.
What are your numbers, and who's coop are you moving which group too?
I always try and think of integration as a plus and minus game. Home front - plus, moving into a new set up minus, larger numbers in the flock +, smaller flock -, older birds +, younger birds -,
bigger birds +, smaller birds -.
Have hide outs, a one way gate for smaller birds, multiple water and feed spots.