Wild ducks? I would get them to a rescue as soon as possible. Keep in mind it's illegal to have them in captivity.
For now, or if you can't, set up a brooder, either out of a kiddie pool, a box,or a large tub. Line it with puppy pads. Don't use newspapers since its slippery. Get them a water bowl that they can get their whole head in, but not their body. Be sure to get proper food. Read
@isaac s thread on niacin deficiency. Setup a headlamp too. 90F the first week, and lower it by 5 every week until matching outside temps.
I wouldn't let any kids handle them. They can help if you think they are capable. I would limit any handling if you are to release them.
Give them plenty of closely supervised outside time. You can sprinkle live mealworms in the grass to teach them to forage.
They get their oul glands at 4 weeks, but do t get adult feathers until later. Since in the wild they would be swiming early you can let them in the bathtub, in lukewarm water, with about 2 inches deep. Supervize them and only keep them in there for about 10 mins.
Be sure to dry them off and put them under a heatlamp.
Sorry for bad spelling, I'm on my phone and autocorrect is horrible