When does the pecking stop? They are all the same age, around 7 weeks. Now I have 11 total and 3 of them I am 99% sure are roos. Only two of the new ones get picked on and mostly by the roos. I'm starting to feel sorry for them.
As long as they aren't causing each other bodily harm- let them duke it out. I wouldn't think it would last more than a day or so. Maybe give them some extra places to hide so they don't become to stressed. Chickens can be some harsh little critters. Good luck!
We have a semi enclosed area and the 3rd one hangs out in there eating and drinking a lot. We pen them up at night and when I checked up on them before I went to bed they were sleeping with each other.
That's a good start. I bet they'll all be one big happy family soon. When I add new birds to my flock- I always add them at night. They always wake in the morning and act like the newbies have always been there. Not sure if this is the way you did it, but its a thought for the next time you add on to the flock.