If those temperatures hold they will need heat for another two to three weeks. Many people are allergic to chicken dander which compounds the issues with brooding indoors. It can be a rough situation to be in.
Can you provide electricity in the coop? Do you have an outbuilding like a workshop or detached garage where you could put them? As a last resort, maybe an attached garage to at least reduce the dander? Can you build an outdoor brooder that keeps them dry, out of the wind, and is predator proof that you can heat?
Brooding in the coop is optimum as far as integration as long as they can see each other. Then you can use the method above and have them integrated really young. A brooder in the run is pretty good too. If they can see each other then use the same method as above. Even if they can't see each other when very young you can put a fence around it and use it as a base for integration.
A lot of if's. That's a problem of not knowing what you are working with. If you cannot brood them in the coop or run, once they can handle the weather put them in a "look but don't touch" situation. House them across wire for a week or two before you let them mingle. Give them as much room as you can. The chicks need to be able to run away from and just avoid the adults. You can improve the quality of what room you have by adding what we call clutter, that's stuff they can hide under, behind, or over. Having widely separated food and water stations can help, especially if they are not in line-of-sight of each other. I've never used
@azygous panic room method, I've never needed it, but especially if room is tight and there is sufficient size difference (adult bantams can mess with this) it can really help. You did follow those links didn't you, like a good student?
The more we know about your situation and what you have to work with the more specific we can get with our suggestions and the more "if's" we can avoid. Good luck with it.