Introducing new chickens

It's been almost 2 weeks and they are still picking on them. The new hens are close to the same size but definitely are intimidated by the others. They pretty much stay on the outside roosts but will come down when I'm in the run, but otherwise they get picked on and jump backup above ground. I want them to all get along and quit picking on them...

How long do I have stress about this? I thought a couple of days but it's not letting up. Tried separating them in the same pen but they get out and go back to sitting on the roosts. They even sleep outside at night instead of going into the coop...