Mixing new chicks in with year olds????

[clara's chickens]

my family and i have 9 hens, 2 of our dominiques went broody on us. we took it as an oppurtunity to acquire some more ameracaunas for our flock. we also came across the black copper maran, such a beautiful chicken and egg, and decided to purchase some of those hatching eggs. because of the set-up of our chicken tractor (specifically grate flooring) i thought it would be best to move the broody hens to their own brooder pens. i am beginning to rethink that choice because now i am not sure how to re-integrate the brooder hens and the newbies. anyone have any tips??? currently they are all fenced in together in about a half acre. so the brooders were never really removed from the flock completely. the brooder pen is basically a crate that came with our high tunnels turned upside down and with a wooden nesting box. all it pretty much ground level. and all the chickens are able to see each other. any help very much appreciated!!!!