I have 10 hens and one rooster. They are all gold laced wyandottes. I have about a dozen eggs in an incubator and am planning on introducing those chicks into the flock. At what age would the chicks need to be? Should I be worried about the hens or rooster being overly aggressive with the new pullets? I had a hen get broody and raise some chicks but that was easy because she took good care of them. This is obviously a different situation. Also, do you are anybody you know vaccinate for merricks or any other disease? Thanks.