I think keeping the drakes and roo penned together isn't a good idea but free ranging they should be okay together as long as your drakes don't think your hens are free game and try to mate with them when they get older. My rooster rules the roost with even my big Muscovy drake and he is game/game bantam so not a large roo at all Only bird he'll back down to are my 2 geese.
I'd be more concerned about the roo maybe pecking one of your boys in the eyes that could be serious.
I'd be more concerned about the roo maybe pecking one of your boys in the eyes that could be serious.