Bullied duck not doing well?

[Purra]

Also a question if anyone wants to answer here.

Is there a minimum number of eggs you can leave with a female that she'll hatch? I can't have a whole nestful of ducklings running around, but I'd like to let them keep two or three.
Of course, then there's having to keep them safe from the drakes. I don't know, just asking for future reference. They aren't even laying yet, and it's only hypothetical.