I am very relieved to have successfully mixed my 25 new chicks, now ten weeks old, in with the 17 two year old hens. I started when the little ones were about two weeks old, putting them in a "play pen" wire structure near the hens ever day that the weather would allow (from 20 minutes to several hours depending on February temps). After a couple of weeks I would put one hen at a time in with the babies while watching them. As they grew they were moved to the orchard run during the day and our grain room at night - I had to get them out of the cardboard box inside!!! I gradually started letting the flocks mix in the larger pasture while watching them for bad behavior. I had one BR with a bad temperament, she would chase and peck the little ones but nothing serious. Now the funny and unexpected part: my BO Emily went broody on me twice last year. She was very low in the pecking order until the chicks came along. It seems to have triggered something in her, and changed her order in the flock even though they are not her chicks. Now she fights the other hens rather than running away. She went after the BR who was chasing the chicks and really let her have it at least twice when I was watching! I have not seen the BR chase the chicks since... I was able to free range both flocks last week, letting the hens wander and keeping the chicks close the the pens. Then I put both flocks together in the large pasture for two days with no problems. Saturday I had to be gone, so I left both flocks in the orchard (smaller area but still large enough with good fences) with no problems. Sunday night I decided to put the chicks in the coop. I went out and the poor things were crying to get back to the grain room that was home, I had to pick each one up and put them in the coop, they were really scared. I was so pleased last night to go out and find all but three had put themselves in the coop by them selves and up on roosts! The only real problem, still existing, is making sure the chicks get access to enough food. The hens can hog the feeders if they are not free ranging. I am letting the hens eat the chick grow food, but they also are eating lots of grass and insects (the grasshoppers are out) and have oyster chip at will. I just love all my pretty girls and the three cockerels in the new bunch.