Just a bit of past experience with a White Leghorn and Cuckoo Marans around our 2 Silkie Hens:
The Marans was nasty to the Silkies and the White Leg. She tried to depose the alpha Leg but the little Leg put the Marans in her place! Next the Marans sat next to one Silkie at night on the roost and pecked her bald (we thought the poor Silkie was molting until we caught the Marans chewing on her). Next the Marans viciously attacked the other Silkie and that was that! We re-homed the nasty Marans.
The White Leghorn was a very kind gentle alpha hen for 3 years and she was nice to the Silkies. However, after her 3rd year molt she emerged aggressive/assertive toward her flockmates and we had to re-home her before she injured the Silkies. We had to re-home a Buff Leghorn pullet who was too aggressive toward the Silkies and toward our gentle Ameraucana. Apparently Leghorns have a cannibalistic aggressive nature - we were just lucky to have the White Leg for 3 gentle years before she went ballistic on her flockmates. She is in an egg-layer flock now and much better suited to be around other assertive breeds like herself.
Not to alarm you but Red Sexlinks can be assertive hens also. If you are thinking about adding Silkies to your backyard I would like to gently suggest keeping them separate from the LF. And if you get Silkies, get two rather than just one. It is a lonely existence for one Silkie alone. We find our Silkies are great layers of 1.25 oz eggs (5 to 6 eggs/week their first year). But they are a very broody bantam so be aware that their egg production output is less because of how often they go broody. They can't help it - it's what they do best!
In Norco there is Amber Waves Silkies if you are looking for a Silkie breeder in the IE. They were featured on the Tori Spelling TV Reality Show a couple years ago. It's where I plan to get my next Silkie pullets if they're still around then.
After our experience mixing LF egg-layers with bantam Silkies we no longer keep assertive egg-laying or dual purpose breeds with our Silkies. We only have 5-lb-&-under breeds in our flock - two Silkies, one Blue Wheaten Ameraucana, and one Blue Breda. Having large heavy dual purpose breeds with Silkies in a small free-range backyard didn't work for us. We only have gentle non-combative breeds and there's more peace now. The kindest bird we ever had around the Silkies is our Blue Wheaten Ameraucana - she is a kooky jittery wary jumpy breed but she is very submissive to both Silkies and has never been combative - she would rather flee than fight!