We had 3 peachicks given to us about 2 weeks ago,they looked to be 3 weeks old at the time,now we have 12 peachicks we hatched that are just 3 weeks old,and are ready to get out of the brooder,,question:,,can we add the 12 younger chicks in with the 3 older ones okay? Do they fight or try to set up a pecking order?