introducing hens to a flock

Did you introduce them properly? (the pecking order never goes away...)

If not, I would separate them again and make a holding pen for them where they can see/have very limited interaction with the rest of the flock. A fenced off area of your run or a carrier cage (if it's big enough) can work. Look at the threads on introducing new birds to the flock

I introduced my new girls, 8 of them, to my current small flock of 3 older girls...what I did was place a baby corral outside everyday it was 65/70 degrees or more for about 2 hours and let the mature hens check them out and hang out with them without actually being able to get to them. I did this for about 1 1/2 weeks, put my new girls in it to get used to outside, etc. before they could officially be left in the outside coop. I then let my older girls out to free range and locked the youngs ones up for most the day for another week to get used to the coop.....We extended our run, placed 2 feeders and 2 waterers on opposite ends, let them all free range together....then when the older girls retired for the evening, the new flock wandered in and made themselves at home. There will always  be a pecking order and it's natural. The only time I would be concerned is if they start drawing blood. If that happens, somehow divide your coop/run and separate them a bit. Putting them all out together to free range is the best way I think as they will have plenty of room and places to run to if the older ones start picking!! I also waiting until the younger ones were almost the same size as the older ones....that helps too!! :))