I agree with @rebrascora if the one that is picking at her has just come into lay, that would be a contributing factor. Coming into lay they can become bossy - think teenage girl that gets ticked off easily - her hair, makeup and clothes are just not suitable and they go into a hormone filled pity party or just get angry for no reason - they just don't seem to know which direction to go, happy or sad LOLYes, this has a lot to do with it. They are adolescent teenage girls and those hormones can cause them to become bossy or shrinking violets. Some pullets at point of lay will even become aggressive towards their owner. Hopefully it should settle down once they get over this initial surge.
Hopefully she will settle down - once all the pullets began to lay they can become a bit more cohesive.
