I have two silkies in a mixed flock of 19…I have very carefully integrated 15 new chickens to my original flock of 4, 2 which were the silkies. I think the above posters are right that it will be tougher to add them to an existing flock of 12, unless you are adding like 6 of them so they have safety in numbers. I would also wait until they are pretty full grown before any attempts at integrating. My younger pullets actually are put in their place by both silkies even though they’re way bigger :-D You can see from the pictures the size differences
I also chose breeds that are really mellow and easy going so none of them really bully…at least not yet. 

