I am seeing some yellowish on the front of the Silkie, but I still think it is going to be a black one. I have a couple just 3 weeks old in the brooder.
Duckling might be khaki.
Your "Runner" looks like a Khaki Campbell. Where did you get it, from eggs or buy a duckling somewhere? Runners do come in Khaki, but it is a rare color and the duckling's body shape right now does not look very "Runner-esque".