She's a normal momma hen. They will drive other hens away from the nest and their chicks when they hatch. I would allow them access to the same space though. It won't be long before mom will be parading her chicks around. Yes, she will continue to drive off the other hen from her chicks but as long as there is enough space, she'll be fine. Once the broody weens her chicks, she will rejoin your other hen.No, she just seems lonely/bored. Broody is in a separate coop as she was frightening the other girl away from sleeping in the coop, she’s really mean!
When the chicks mature, they will integrate with their mother and "aunt".
What are you going to do with any cockerels you hatch?