If you want to keep all the boys I'd give them a one roo to five hens ratio. Normally it is a one roo to ten hens ratio, but I had a silkie breeder tell me once that the 1:5 is what she does.
There may not be a problem until they try to all mate the hen at once. I'd not allow that. So you can just wait until you see mating. When you do, I'd get the hen out of there with another boy for company.
Silkie boys get along pretty well from my experience...just some pecking order adjustment. If you want to keep them all and hatch out some more, you can put the hen and one boy in a pen by themselves, and keep everyone (fix a bachelor pen for the boys).