Let your original birds out of your set up into your yard, and lock the new ones in the coop/run. This lets them explore the set up without being chased. At dark, put the new ones in a kennel, in the coop and let the others come in and roost.
Rinse - repeat. Feed along the fence.
Do make sure that you have hide outs in your run, so many people just have open rectangles - add clutter, boxes, totes, roosts, things birds can get on top of or behind and out of sight. Add extra feed areas where as a bird eating at them is out of sight of birds eating at another one.
3-4 night, let the old birds in pretty near dark. Have ample roosting space in different places in the coop.
Mrs K