Integrating 2 New Pullets 8 weeks Old with 8 6 week olds
It is hard to add less to more. Was hoping the slightly bigger size might help. It didn't.
What doe your run look like? Is it just a single level open rectangle? I see a lot of those on here, and they can cause problems. They look like a lot of space, but it is all open, and birds can't get away from each other or out of sight. You need to add some hideouts, but do make sure that each hide out has two exits, so a bird cannot get trapped in there.
Add a pallet up on a single row of cement blocks. Little birds can get either up on top or down underneath. So while it looks a bit more cluttered, it actually doubles the space. Lean a couple of pallets against a wall, so that a bird can walk behind it, get in a little shade, get out of sight of other birds. Set a pallet straight up, then put feed and water dishes on one side, and clear across the pen on the other side add some another feed bowl and water. Add a couple of roosts out in the coop too.
This will give less dominant birds a place to escape. In chicken society, two birds approach each other. The less dominant bird gives way and often times leaves the area, getting out of sight of the dominant bird. A big problem is when there is NO WHERE to go, the dominant bird takes offense and attacks again, a bit harder to prove her point, and eventually it gets rather brutal.