Good head hens will intervene in squabbles between subordinates...just like a good rooster would.Another update:
Added an outdoor additional run area, let the 3 free hens out this afternoon. Opened Penny's "run cage", and let her come out on her own. Had 2 minor skirmishes between Penny and the lower 2 in the order - each was only 1 on 1 conflicts. Quite interesting that #1 Hen seemed to intervene in the 2 conflicts. Penny retreated to her cage after the second skirmish. At this point am more optimistic, planning to try this over and over until success.
Patient repetition of co-mingling can work...have done it with chick groups.