About Silkies, and introducing one bird at a time. Not best, better to introduce at least two, or more, if possible. Silkies can't fly, or manage either high heat or extreme cold. Those cute feathers aren't efficient at all, and in general this breed is more fragile than normally feathered birds. Many people with Silkies have a separate coop for them.
We started with Belgian d'Uccles and Silkies from a neighbor, and no knowledge about them. It didn't go well for the Silkies, and we've never had any again.
Can you build a wider run? At least five feet wide, or more, will work better for managing flock interactions.
Mary