Typical behavior. As long as they aren't drawing blood, pinning them down and pecking mercilessly, and cornering them, I wouldn't interfere. Do you have room for multiple feeders and waterers? How about room for hiding places for the little ones?How long should it take for the pecking order to be established for my flock now that I've combined? The older girls aren't being overly aggressive, but they're making sure the younger ones don't eat or drink until it's their turn. Also not letting them into the coop at night.