Don't underestimate the problem here with your 3 year old and this rooster. Adults can learn to "read" a roosters behavior, learn when he's thinking about attacking and react appropriately. A 3 year old child is not capable of this in my opinion. Also they are smaller, tend to make quick movements, maybe loud noises, roosters just tend to want to go after them before they'll go after an adult, easier target. Children are short, they are at much greater risk of serious injury with a large rooster who jumps up, attempts to spur and maybe pecks as well. It's just not worth keeping a bird like that around and risking an eye injury or other injury to your child.
As far as your pair of Silkies? Yes he will continue to attempt to dominate the male and take possession of the hen. Silkies are often not a good match to be housed with standard breed roosters.
To be honest, I'd not be spending time trying to reform this bird, a rooster has natural ingrained tendencies and some of them can be pretty nasty. If you are lucky enough to get a nice rooster that's great, but a nasty one is just not a good combination with small children.