I have had black sex-linked hens for 2 to 3 years. Good-natured egg-laying hens. Love them. I started out with 6. Two were stolen out of my coop. I've since added a keyed lock to keep human thieves out. I am getting some Mille Fleur d'Uccles and Whiting True Blues chicks soon. Has anyone had experience adding new birds to a small flock of mature black sex-linked hens?