I know you love your ducks and having ducks in general, with an interest in learning more about them too. However, have you thought about NOT incubating the eggs since you seem to want pure bred ducks, and possiblly a different breed? It makes more sense to not hatch ducklings that there is no long term plan for.  I would suggest slowing down on the adding more and more until you know what you really want/breed you are most interested in. This way you aren't having to feed, house and worry about various ages of ducks. Find new homes for ducks you can't keep or don't want that particular breed. I would have to say that just because there ARE eggs and they could be incubated, doesn't dictate that they have to be incubated. Collect the eggs, use them in baking and cooking, maybe find someone to share the eggs with locally for eatting and be happy with the ducks you have.