New pullets picking on my hen.......

[cabela]

I have a pullet that is about 2 months old,(Camo), just got rid of her rooster brother and bought 4 new pullets that are a few weeks younger, the new ones are Buff Orpington, Lancaster cross. Right away one of them started picking on my girl Camo, she is an Americauna. She is very afraid of them and I don't free range. She runs and keeps to herself, is there a way to "discipline" the one that is being mean? I am thinking eventually they will get along, how long does it usually take? Thanks........