Interesting thread, hard to tell. 'Only' from the first photo the shape and profile looks female to me. I understand that this is the dominant fish too.
This is more likely down to the introduced fish invading her space, females can be just as rough as males. I'm not sure about the other fish. Sub dominate behaviour dosen't mean female either.
The introduced fish appears thicker on the photos, so could be a male.
Obviously this is only going from looking at the photos. You would probably have a better idea watching them.
You will certainly have your work cut out trying to get two mature fish to pair.
Good luck on the project, hope it works out.
Lee.