what age to intergrate chicks?

[dntd]

I have 4 bantem oegb and 11 chicks( trying to sell 5 of them though) they will be 3 weeks on monday, what age do I introduce them, my roo is really good to his girls buy IDK about some strange little ones. Should I let them see them?how should I do that? they will share the same run but not the same sleeping area.