Can you post photos of your set up? It didn't sound too bad at first description, until you got to the part that the bullied hen spends half the day inside just to hide from the bully.When she catches her she pecks her maybe once or twice, but it never results in any injuries or missing feathers. In general the bullied hen eats and drinks just fine but usually gets bullied out of treats. The bullying seems to get worse throughout the day to the point where the bullied hen ends up spending the latter half of the day staying inside the coop to get away from the bully.
Is this normal behavior in re-establishing the pecking order with the newly smaller flock?
Is the flock TOO small and in need of a few additions?
Any suggestions for curbing this behavior without separating the bully?
Adding MORE birds to a bullying situation is probably not going to help - someone has to be bottom of the pecking order, and you may end up with more bullied birds, or more bullies.