I wanted to get a 6 month old pullet to put in with my 3-4 month old pullets but I ran into the problem of feeding them. My chickens are currently eating Purina Start & Grow and should be on it until they are 18 weeks old but the 6 month old pullet would need the adult food. Could I start them on the adult food early or the other way around for the new bird? Or will this just not work and I need a bird the right age? I'm new to chickens and I really need help with this!