Ducks still not laying ?
How many ducks, how many drakes, what breed? What feed are you using, are you giving free choice oyster shell or other calcium supplement?
From what I have read here and elsewhere, the best number of drakes to ducks is one drake for three to six ducks. When there are more drakes, and even sometimes when there is just one drake, a female can be overmated and that can stop egg production, cause injury, or even kill her.
Multiple drakes may gang up on one duck.
I would omit the scratch for now. Egg-laying requires lots of nutrients, and scratch has calories, but not many vitamins or minerals that the ducks need to lay eggs.
You may need to be creative to be sure the ducks are getting what they need - safety, good nutrition, plenty of the right minerals.
What is it that is hard? Making sure they get extra vitamins?
Yes, I have heard about goats!
Still, if the ducks need something they're not getting, there must be a way to get it to them.