khaki campbells going broody?

We have 4 young KC hens, about 6 months old, who are finally now all laying every day. They have been in with a drake for about a month. It took a long time for 2 of them to start laying, and when those last two started, there started to be some nest activity. before that the eggs were just wherever on the coop floor. Now every morning there is a little nest dug out of the straw with all four eggs in it, but when I go to open the coop they all panic and stampede around like maniacs and go running outside. I get their food and water and stuff and they go about their day, rooting for slugs and what not, eating their food, playing in their bath. I gather up the eggs, since we had no plans to hatch more ducklings at this time, and they don't seem interested in actually sitting on the nest.

I'm interested in the nest building though - do you think if I left them alone they would actually incubate these eggs? All 4 lay every day so if I let them sit and didn't gather, they'd soon fill the coop with eggs! If I did want to let them try hatching a brood, how would I go about that? If I let them sit, would they stop laying? How much time can they spend off the eggs before they eggs 'go bad'? Ie, maybe I could let them have a go, but if I see that they're off the eggs for too long every day I'll cancel the experiment.

I've heard that KCs make bad mothers so I didn't have plans for this, but I'm always open to new plans

That's cool to hear, I sure miss duck eggs, they are so so soooo tasty. Our Khaki's used to do the same cute little nest thing. They never got broody however, even if we left a big clutch of eggs. They would just amass a mountain of duck eggs! Always seemed way to nervous and hyperactive to do something as contemplative as sitting a clutch of eggs.
If you do manage to get one to sit, please share. Would be a real success.
Enjoy the quiche!

I have two flocks of KC. One flock is a year old and includes two drakes and three ducks. The other is a young flock of 10, sex unknown.
The older birds will make a nest in the pen sometimes, and lay there or they just lay anywhere on the pen floor and sometimes in the coop. I let them out to range every day and sometimes they will lay out somewhere. If I let them out too early they lay outside. Twice I found a nest near the creek where they had layed four eggs over a few days. In addition to that I find eggs anywhere and everywhere, in the berry patch in pathways etc. Seems when they are ready to lay, they squat and let it fly.
I have never seen them sit on eggs though. I am thinking of putting some eggs under one of my broody hens or getting an incubator to try to hatch some out.
My second season chickens are not laying very well and don't think the eggs are worth what I am feeding them, even though they free range. The ducks are certainly worth it as they forage most of their own food and lay almost every day.
I think I may phase out chickens and go with several flocks of Khaki Campbell layers.