We bought chicks from IFA this year and they are now about 6-7 weeks old (5 chicks). I've put them outside in our coop and they're doing just dandy. My niece volunteered me to take the chicks that her school class hatched, and they are now about 3 weeks old (3 chicks). I've never had two broods of chicks to combine, at what age will that go most smoothly? Any tips on how to do it?