Just picked up my new 6 hens 4 days ago. First time every for me to have chickens. They are Isa Browns - 10 months old and they each are laying an egg a day except for one - I am sure she is still ajusting to the new place. Anyway I was going to add a couple of different breeds to the flock - but - the farmer that I got them from said not to put another hens / roosters in with an existing brood as they will kill the new bee in the bunch. What are you thoughts on this or any advise?