Here's how it worked w/ our flock. We had an older established flock of 9, 8 pullets and 1 cockerel (the big boy in my avatar.) This spring we bought 16 chicks. The older ones just turned a 1 year old last month. We gradually introduced the babies during free range time, as they're much faster and could easily run and hide under cover if need be. They were right around 6 weeks old and very tired of being in the brooder (flying out all the time.) They had their feathers and were around 3lbs. Old enough, big enough and protected enough to be introduced.
It was a complete NON issue!! For the longest time the older ones completely ignored them and they stayed in two groups when foraging. I was also feeding them seperately. After a few days the babies started mingling in w/ the older ones until they became one large group.... safety in numbers type of thing. The cockerel would eat w/ them and not pick on them at all. The older girls did pick on them some while feeding and drinking, occasional head peck saying "that's mine, get away" and the babies learned quickly to stay clear of them while eating and drinking.
The older ones are now over a year old and the babies will be six months old on the 14th. They've been together since the end of May. They're one big happy family and get along fine doing anything at the same time now. Even when I hand out treats. They all share or take turns.
As for breeding. My babies are little hussies. They squat in front of the rooster, like 3-4 at a time sometimes, and he completely ignores the poor girls. I think he's racist!! The babies are black and he and his girls are white w/ black. LOL These are all LF, as well. The rooster is 3x bigger than my baby girls. I'd be afraid he'd squish them.
Good luck and HTH.
