I have 3 groups of chickens, different ages and breeds that I can't blend peacefully. The oldest ones were here first and one of them is at the top if the order. Two groups are ok roaming the yard during the day but refuse to sleep in the same coop. The hens attack any other chicken I try to put in the coop at night. How can I blend these 3 groups successfully and with the least amount if violence possible? Thanks everyone!