The chicks won't be headed outdoors for at least 3 weeks or so. And I wasn't going to put them together with the bigger hens but I really have no experience with integrating chicks and hens so opinions are welcome! I can segregate or integrate the bigs and littles.
I find that sectioning off part of your run or building a temporary run next to the full grown chickens works for me. I place the younger chickens in the protected area with food and water so all birds can see each other but the large birds can not hurt the smaller ones. After a couple weeks I let them free range all together for an hour or so a day and once I'm satisfied, I'll put the young chickens in the coop at night. Everyone is different so you might find something else that works for you. Just make sure the chicks are old enough to defend themselves and have places to hide in your run. Good luck!