I've been considering getting 5 serama bantam chicks. The only problem is that I'm not sure if I will be able to mix them with my 15 two week old chicks? Oh and if helps, I have 5 RIR, 5 buff Orpington, 2 light brahmas, 1 red star, 1 silver laced Wyandotte, and 1 barred rock. They are all pullets except for one if the brahmas, which we expect may be a rooster. Is it safe to mix?! Help!