I have raised my chickens, turkeys, guineas and geese all together, in the same coop and free ranged together. My inderstanding is this:
Chickens can be carriers and unaffected by it after about 6 months. It is almost always fatal to turkeys and other fowl. So to stop the potential spread from chickens to the other fowl, you are supposed to separate them.
I live in MIssouri and Black Head is rather rare around here. And it'e kind of like measles: Some one has to have it in order to pass it on to the next animal. Now some people are real fanatics about this and separating their birds. Me, I've always gotten healthy chicks from the hatchery and raised them together. Never had a single problem.
Hope all goes well for you.
And yes, I'd put them back in with each other. They become family and I swear some of them don't know they are different than the others.