I have 5 hens and one rooster (7months old), they have a coop and a large yard. I'm building a second coop and small yard for future chickens. In November I am getting 3 - 4 month old Silkie hens. How long should I keep them separated? After that period of time, would it be good to put one or 2 of my existing hens in there with the new ones for a few weeks then introduce all back together? Thx!!