In my personal experience, roosters that are raised together fair a lot better then having older and younger roos introduced or two roosters of the same age but different flocks put together. I think that when they are raised together they figure out the pecking order a lot sooner and don't have as big of a quarrel.
I've had two pairs of roosters that were inseparable.
The first pair were Seramas. We got them from a someone who was rehoming them due to the other roosters and hens bullying them. The second day we had them, one of the roosters, Rusty, flew away into the woods ( we were moving and he jumped out of his box after unpacking from the car). The other rooster, Dusty, went into a deep state of depression. He didn't want to eat or drink and just sat there with his eyes closed. I'm sure he would have died of heartbreak if we had not found Rusty three days later. I never once saw them fight and they took they shared the spot of top rooster. They would gang up on any of the other roosters that came near their girls and polity took turns mounting the hens.
The second duo were Favaucanas. They were the only chicks that hatched out of twelve shipped eggs. They imprinted on each other I suppose. I was disappointed to find out they were both roosters, but ah well. They were barely a few years old when the dogs got to them. They tried to protect each other but both lost in the end.
You won't know for certain if they will continue to get along or if they will break apart until they are older. 10 weeks old is still young to be certain of a Silkies age.