Best way to intriduce new cockerel

Hey guys
I currently have  8 silkie hens, true miniature bearded, 5 white, 2 black 1 cuckoo all girls n 1 black boy. I wanted a mini white boy n hatched some eggs, unfortunately the cockerel was way too big for little girls. The mini cockerel didnt mind the larger young cockerel even when he started treading girls. Still he was too big n had to go 
So I now have a small white cockerel, had him in isolation for a couple of weeksn then had him in an a frame for 8 days so others could see him.This morning I let him out big fight and it is the black that was taking a pounding, I had to break it up as they werent gona stop  . Mini blacks are very difficult to come by n he is very nice natured, the white is a very nice bird,few months older and is very much the agressor, is there anything I can do?
Or would I be better off hatching in spring n using a cockerel from the new batch, working on the assumption that if they grow up together they may get on better 

I have a large garden n 2 henhouses so cockerels are housed seperate, dont  want to keep them locked up - any suggestions?

thanks, both henhouses hav runs but mostly they free range in garden. I have put up temp wire fence n will give it 1-2 weeks then make a decision. Think hatchlings may be way to go.

Thanks again 

Would suggest splitting things up and having 2 families of hens/cockerels and keeping them separately. The problem will only get worse in the Spring and I fear the outcome!