I've raised rabbits for a few years and I think the easiest thing to do is to separate them once they start being aggressive and dominating. With sisters, they can sometimes be housed together, but my
experience is that once they get to breeding age, they start to want their own space. It's understandable, I guess.
Males are worse for sure. They will actually try to castrate each other if kept in too close of quarters after about eight weeks of age. When I was expanding my herd, I would keep sisters together up to about four months of age. After that, they got their own space large enough for them and a litter of kits. It was just easier on my mind, knowing that no matter how much foot stomping I heard at night, everyone was safe in their own space. I never had it happen to me but I have read about people waking up to find one rabbit has killed the other. I imagine one rabbit could eventually just wear the other one out with stress if it had the conviction.
Mounting and hair pulling (usually from the back of the neck) is how a male holds on during mating. It's also a universal sign of dominance among either gender. It's hard to say if it will get worse, but if there is a way to give each doe her own space without being bothered by the other, that would probably reduce their stress and yours. It is possible that they are doing some damage by hair pulling, biting and scratching. Over time that damage adds up.
It sounds like they would have plenty of space if you just added a divider to the space they currently share. 4'x3' of space is good. Maybe they could be separated when you aren't watching them, but you could let them play together as long as you have an eye on them. If crappy behavior starts again, everyone goes back to their own space. You might even be able to teach them to play nice.
Good luck