Hello Harri, and welcome to BYC!

Glad you joined.
The Silkies will never be good a free ranging. You might need to pen them in a covered run to do your breeding project. Maybe you can breed some predator awareness into them but the floofy feathers on their heads inhibit good sight so...
My flock has had many hawks strikes here but I've only lost one bird and have had no injuries to any others. I myself have been witness to 4 hawk strikes and I'm certainly not out with the flock constantly so there must be many more that I've not been around to see. Lots of eyes to the sky and lots of good cover are key. I still feel bad for the hawk and too hope it wasn't carrying any disease communicable to your flock. We've had raptors come up positive in this country for HPAI.