junebuggena
Crowing
You can try removing the aggressive bird for a few days to reset the pecking order and then add her back in. It sometimes works for a young girl that's just getting a bit too big for her britches, so to speak. She will basically be a 'new' bird. Being the smallest and 'newest' in the flock, the others should make it clear that she's at the bottom of the order. If she is truly an aggressive bird the only solution may be to rehome her, with full disclosure about her temperament.
Your EE, Australorp, and RIR are considered large breeds. Large breeds need about 5 sq ft in the coop and at least 12 sq ft in the run. With you estimate of 144 sq ft available, you have enough room for about 8 large breed birds, not 9. Extra Large breeds like standard Cochin, Brahma, and Giants need even more space.
Your EE, Australorp, and RIR are considered large breeds. Large breeds need about 5 sq ft in the coop and at least 12 sq ft in the run. With you estimate of 144 sq ft available, you have enough room for about 8 large breed birds, not 9. Extra Large breeds like standard Cochin, Brahma, and Giants need even more space.