My 4 drakes are still skirmishing -- when they start making one drake's life a misery in the coop, I now put the bullied drake, a crested pekin, in a dog crate in the coop with his own food and water so that he is undisturbed in there. I previously took the bullied drake into my house, but the ducks want to be together -- even the bullied one. So, I tried dog crate protection in the coop. It worked although allegiances also changed with previously bullied pekin teaming up with alpha male muscovy, and other muscovy no longer so close the alpha male muscovy
Then I got a fourth drake, a regular pekin. I introduced using see no touch and then supervised short meetings then out in the garden free ranging together. After 10 days, I let new pekin drake stay in the coop overnight as he went in the coop of his own volition. He was then bulled by the 2 muscovies and excluded from food. I left them for 3 nights, but tonight changed the arrangements as the regular pekin is losing weight.
Tonight I put the regular pekin in the dog crate and let the crested Pekin take his chances with the muscovies. He was initially bullied by one muscovy, but quickly jumped up on to the higher level next to his buddy muscovy. That resolved the problem for the night as the second muscovy would have to get past buddy muscovy to continue pecking at the crested pekin
It's all very distressing for me, but my son [who has a flock of females] thinks I should just leave them to work it out. I am still working on sleeping arrangements to reduce the bullying in the coop, but I do leave them to work it out in the garden during the day.