My husband friend is coming to get the roo and I will introduce the barred rock to the group and the roo that I already have ... His friend has 6 hens with no roo's and lives in the country his fee range so he will like that I hope ... The barred rock I hope will do ok with the flock and not miss the roo ... Each other is all they knowIf you want to keep him get them together ASAP. He is young enough to be fine with your other roo. If he grow up with him you shouldn't have any problems.
