The second coop is next to the first. They have been seeing and hearing each other for over a month. There is only a short wall, and wire separating them. They have also been mellow in the past when introducing new chickens. The issue is more about food. MOST people agree that medicated feed should not be fed to hens if you are eating their eggs. I know it is SUPPOSED to be "alright" but I just don't think so (that made sense, right?). I am looking at waiting until I am out of the open bags (which will be about 3 weeks) and go with a non medicated for everyone. The chicks will also have another growth spurt or three by then. Are you saying that you disagree that 8 weeks is the right age to merge flocks? What age do you feel is best?