Getting a few new bantams would probably help, imo, because large birds are likely shift focus off silkie and silkie will be dominant over new bantams...at least for awhile. The new bantams may or may not become her friends, but either way, she will no longer be at the bottom of the peck order.
The issue is that then space becomes tighter, and it sounds like you don't have a lot of space to begin with. If they go outside for most of the day, year round, then getting a couple of new bantams might work. But if they have to spend a substantial amount of time confined, then, to be honest, I'd rehome the silkie or find a way to change your set up and/or management so that silkie can stay out of the way of the big ones and still have free access to food and water.