I'm not sure what happened with your "escape and mingle", but if it was indeed brief and before they were showing symptoms, I would hope my original flock hasn't caught anything and would get rid of both new hens. Get rid of them means either return to the person who sold them, or kill both hens. If they're on antibiotics, unfortunately you won't be able to use the meat from either hen. Just don't resell to another unsuspecting flock owner.
