I need some advice, but first the background: I have two 1.5 year old hens - a Sicilian buttercup and a red star. On Thursday I got two almost pullets - probably 7 month old - one Wheaton Americana and one black copper maran. They are all sleeping in the coop together but everyday I have to go into the coop to bring the youngster into the run alone because of the aggressive red star. Today I let the two older gals free range most of the day outside of the playpen and again I went into the coop and pulled the new girls out and put them in the playpen (10x10). Everyone was very happy. The new girls found the water and food and scratched and explored. The two older girls mostly hung right around the playpen so they were very aware of the presence of the new ones in the playpen and do not squawk at all about it - big improvement from the day before. Following a suggestion of my neighbor, at about 1pm I put just one of the older girls in the playpen - the less aggressive Sicilian buttercup - and left the red star outside. The buttercup asserted herself but without chasing or pecking. After a few hours, I let her back out to free range and brought the red star in the play pen. She seemed agitated that the butter cup was not in with her, but she also finally settled. All good so far... ... Until near dusk - maybe 4:30- I put the buttercup back in the pen too. Now all four were in the playpen and the red star immediately got very aggressive chasing and pecking (mouthful of feathers) first the Wheaton Americana until she got into the coop and up on the roost, and then the red star came back out to chase/attack the black cooper maran, again until after round and round and mouthful of feathers, she also was in the coop and up on the roost. It happened so fast. I wasn't sure if I should have tried to stop it. I don't think either one was hurt. Tomorrow I cannot be outside all day as I was today and I am trying to figure out what to do. I was thinking I might try again with the new girls and the buttercup in the playpen and leave the red star outside, but eventually we need the red star to be okay and not terrorize the young ones. Suggestions?