Two things: 1) I am proud owner of 6 chickens 3 about two months old and 3 two week old. the older ones live in the coop outside and the new ones are in the warmer. Do the older ones need a warmer in coop. We live in Phx., AZ and the temp is around 45 to 50 for the low. 2) is it difficult to put the three new ones with the older three?