Lotta a. Good ideas here, it's up to you of course but I'll share some ideas too as it seems I always have several ages groups going at all times. When they are free ranging the younger ones without a broody learn quick to get out of the way, the chicks learn quick not to stray too far from mama. In the coop is a different story since they are so confined, I provide smaller perches for the little ones, that the heavy birds can't be comfortable on, and safe places for the chicks to dodge behind. Since you have two coops already, which is ideal, I'd separate both coops into halves, make what's called a crib feeder with slats that only the small chicks can go through, put their food water and perches in there, soon they will know that's a safe place. You will have to supervise them and make sure they know to run to safety. (When getting pecked some will freeze and forget to run!) You might want to make a door that can be closed off completely for times when your not around. I've been told roosters will kill a chick, but I must have some good roos cause they just look at them like they could be aliens...the hens are a little meaner, but it usually comes to a 'get out of my way' peck, bloodcurdling scream from the chick, and all returns to normal. Other than a few lost feathers no harm done. As they get older you'll have less to worry about as they learn to keep an eye on the meanies and stay out of reach.