Help needed integrating new Hens and a Rooster

[semillion2]

I have three hens two Americauna's one Sussex and one Americauna Rooster all around three months old. At present they spend the night in a huge box in the garage and in the morning I place them down the bottom of the main Chicken Coop and draw up the bridge. Then I open up the top section of our traingle tractor place two pieces of board on the outside and just enough opening for the three older hens to go in and lay eggs on the nesting boxes. So the older hens cannot get down to the bottom of the coop. I have eight days left before I go on vacation and need to integrate the young ones to the older ones. I am really scared because our od black Austrolothorpe is really mean and our last Rooster she picked clean off his top head feathers. We do not have a run on our Coop. Also our Chickens are free ranging and they are fenced in pretty good with our creek and fence. I have allowed two weeks so far for the older hens too see the new Chickens. They have walked around the outside of the coop and stuck their heads in to have a look. "Does anyone have any ideas what I can do?" I have seen some real mean stuff with Chickens and I don't want the old hens killing any of the new ones.