If the bully girl arrived with her friend and they get on I would leave them together in a shed of their own. If that's not possible I would pen the bully on her own, but within sight of the rest of them (as in pen in the corner of the shed.
If the bully won't settle in you may have to think about what to do with her in the long-term....
I currently still have a couple of my goatlings grazing at different times to the main flock, as they are still the horrible teenagers trying to mess about with everybody else... and while 5 of the older ones were in-kid I wasn't risking anyone being hit. Will need to slowly re-introduce the goatlings though... am expecting bloody heads