I'm of the opinion that if there's not actual blood being drawn you shouldn't intervene.
Chickens are, from our point of view, brutal. A little violence seems to be necessary to them getting it all worked out. I would be willing to bet that if you let them tough it out for a few days (being ready to step in if you should see serious feather-picking or any evidence of blood drawn) they'll learn to get along with each other and it'll be smooth sailing from then on out.
If you're worried about them eating and drinking enough, arrange for multiple feed and water receptacles so the big ones can't guard the resources.