Introducing the chicks for just during the day is a cinch. All you need is a safe area, I like to call it a "panic room", for the chicks where the big girls can't reach them. You need to keep them separate for at least a week until the big girls get used to the idea of the chicks being part of the flock.
The second week, I open 5 x 7 pop holes in the panic room so the chicks can explore the main run. (Or put up barriers with a seven inch clearance for the chicks to scoot under.) They scurry back to safety when chased of bullied or pecked. Food and water needs to be kept inside this safe enclosure or else the chicks may be bullied away from the food and water, not getting what they need. Also, during this period until the pullets start laying, you should keep them from getting layer feed as the added calcium is not good for growing pullets. I feed an all-flock feed during this time, actually I gave up feeding layer feed years ago since my flock hates the taste.
Introducing the chicks into the roosting portion of your coop/run is going to be tricky. I usually do it two or three weeks after the chicks have learned to deal with the pecking order, having had full access to the run and have been mingling with the flock for awhile.
I install the chicks in the coop early in the day, after the big girls have finished laying, then lock them out, leaving the chicks to explore the coop and make themselves at home. Have food and water in the coop for them since they'll be in it all day long.
At nightfall, let the big girls in. They may or may not harass the chicks. Just referee if they do. If you do it just as it's getting dark, they should leave the chicks alone. In the morning, the chicks will be chased out and they'll know to run into their panic room. You may need to teach them to go into the coop at night by putting them inside. It takes a week or two for them to learn to do it by themselves.
There's an outside chance the big girls will accept the chicks without any drama, but don't count on it. Provide a safe retreat for the chicks and it will go as smoothly as chicken world allows.