Here's what I would do--keep her very separate from your flock for now. Pick a mellow chicken from your flock to put in with her for a few weeks. This will do several things--she will have company while she is in isolation so she is not so stressed and lonely, you will figure out if she is a carrier of some disease before you infect the entire flock, and she will have a buddy when she is introduced to take some of the heat off. When they have been together for several weeks, try free-ranging everyone together, supervised at first, until they are all comfortable with each other.