Black (M) x Splash (F), Blue (F), & Partridge (F) =
1. 100% blue
2. 50/blue 50/black
3. 100% black carrying partridge (simplified)
It's been a few years since I've bred silkies so I'm rusty on chick ID'ing but at face value that's genetically what your flock, but your birds may carry recessive genes or could be mixed color (like how some 'solid black' birds have leakage for example). Someone else who is more recently familiar with chick down ID may be able to help, but when in doubt with some time, once the feathers are showing it'll be easier to ID or guess
My guess without your flock in mind would have been some sort of diluted partridge but if that's the only birds in your flock it'd be impossible. black + black partridge cannot make a blue or a splash, so it couldn't be a blue or splash partridge.
Based on the photo, I was thinking the chick might be blue partridge. Maybe your black rooster carries some partridge genetics? Otherwise, like CascadiaRiver said, blue partridge shouldn't be possible.
I suppose another possibility would be lavender partridge, but it's less likely, as both parents would have to be lavender carriers, and the brown on the chick's head looks a little too dark for lavender.
But I agree that it'll be easier to tell when the feathers start to come in.