Why would you separate them?? She'll distance them herself when she's tired of their demands and thinks they're old enough. I've had hens kick them to the curb before 4 weeks, and others who haven't pushed them aside until about 8 weeks. I think MOST hens do so around the 5-6 week mark. They'll just peck at them a bit when the young ones try to get close or up under them...they'll stop finding morsels for them, etc. I've never had a hen abuse/attack her young when she's done with them...so they should not need to be removed, unless you simply have other plans for them...