Unless you attained your birds from a private breeder of exhibition Silkies, chances are their crests aren't that prohibiting to what they can see. And if they are, you can band their crests.
If you want to baby your Silkies, they do tend to prefer to be housed with their kind. And, the bred does take kindly to babying. But, many people house them with other breeds, and even allow them to range in their yard during the day.
I housed mine with many other breeds and let them range, there wasn't any problems. The Silkies tended to band together, and the other chickens ignored them. There may be bickering for the first few days, and if your cage is super small it could pos a problem if you have a serious bully.
As always, when adding birds do so with other distractions, and make sure your home the entire day to continue to check on them. Try not to be to soft about some basic chomping and kicking.
