Sounds like Mr drake may need some time out. If you can place him where they can all see each other but give the one he is being aggressive to and the other girls some Time off from him. Then maybe start back with an introduction putting the Rouen female in with him first and see how that goes. This is after they have been separated maybe for a
week. You can also use a dog crate inside the coop to keep Mr drake from being aggressive overnight. Many of us use this during high hormones. I have my Runner drake and his females separated from My Muscovy females becasue he just can't leave them alone.
