People are people, and will respond according to their moral compass (among other things). Your question has been answered, and you have also been given some responses from very trusted members on here pointing out the ethical issues in your plan. At the end of the day it's your ducks (apologies, your family's ducks). They might be mating freely, but birds are not like mammals. You can very easily take away the eggs and eat them. Whether or not you decide to do that, it's on you