A lot depends on the hens you are getting. Have they been raised just with themselves, or have they had chicks around them before? I think being that this is a new place to both groups, that is an advantage. I think of integration of plus and minuses.
Home territory - plus
size - bigger plus, smaller -
number of birds, you will have more hens than chicks, so the size and number go to the hens.
I would give home territory to your chicks. Let them get out there first for a couple of days or a week. Also, in the run and in the coop, set up some one way gates, that the chicks can fit through, but the hens cannot. I am currently using a lattice panel that works great for small chicks, but a pallet will work, or woven wire. This allows the chicks to have a retreat to get away from the bigger birds. Yet it still gives them enough space. I am not a fan of trapping chicks in a dog kennel for an extended period of time. The idea is not to trap them away from the big girls, but rather let them run with the big girls with a time out place of safety.
If you stomp around a bit, acting big and mean, the chicks will find these hide outs and escapes before the hens are added. Then I would add the hens at night. Even if you get them earlier in the day, just wait for dark. Hens are nearly comatose when it is dark, they are easy to handle. Place them on the roost.
Do get down there early, so that you can see what is going on, and intervene if necessary.
To correctly quarantine, you need to keep the birds separate by 300 feet, change your shoes when going between set ups, and use different feed and water. Most back yard people cannot logistically quarantine. If you can't, you can't, and pretending to quarantine is not effective. It is not 100%, but healthy tends to look healthy. DO NOT TAKE ANY BIRD you feel sorry for, or really, I would not get anything from a swap or auction. Those birds have been exposed to God knows what. While it is a risk, many of us have added numerous birds, without quarantine. If one is risking very valuable birds, or a huge number of birds, then the economics make you quarantine. or should not add new birds. But in your set up, a small flock, it is worth the risk to me.
Mrs k