I have a gold laced Wyandotte that is 8 months old, she still hangs with her mum. If you wait until dusk, when they are screaming for her to go back to the brooder and pop them up on the perch with her, they will get the idea. My silkie babies roost with the big guys, really cute, the roo cuddles them under him. Unless you have a specific reason for separating them, I would just let them be, momma will sort them out.