Do you know how you will split the hens between the cockerels?
They're a bit young to have favorites so by breed might be a solution.
Biggest hens for your largest cockerel would be one way I would approach this if you can't split by breed.
I feel for you. One of the first fights I had to deal with was a fight to the death between Maran roosters. There was blood and snot all over the place and I really wasn't sure what I should do.
Because of stories like this I seperatex my two after one fight(no injuries) and a lot of challenging. I was in the yard catching roosters talking to my self with a few curse words--neighbors have to think I am nuts. There was no way I was spending any time breaking up fights between roosters. I gave enough to deal with, with german shepherds..