I have 10 bantam chicks brooding together. 5 of them are 3 weeks old and 5 of them are 2 weeks old. I am getting 4 bantam chicks today (my local requirement is an amount of 4) to put under my broody 7.5 month silkie. If she doesn't accept them, is it safe to add them with my other chicks? Also, is 4 too many for my silkies first time?