Yeah, I had to teach my ducklings how to eat haha. I would drop some feed in the water and / or offer it to them from my finger. They should get the hang of eating in a day or two.
Also, make sure they have food and water available 24 / 7.
Yes, please candle them and post pictures. Although, if it’s really been 4 days since she’s sat, I’d be skeptical.. they can only go so long without proper heat. Do you have an incubator??