Can you add adult hens to a flock of 6 week olds? if there are only 2 new chickens (maybe 2 females or maybe one of each) will they do OK? Someone locally is selling phoenix and yokohamas and I'd love to get a pair. my flock outside is 11 6 1/2 week olds. Will the new chickens pick on my babies? I was hoping because the 11 have been together that there'd be strength in numbers. The birds I would be getting are over a year old. Thanks!