I have 8 Muscovy ducks and 2 drakes. The females go broody in teams with each team sharing nesting duties. They are not above stealing from each other. Very funny to watch one duck try to casually roll an egg from one nest to theirs.
I would recommend dating the eggs on the day their are laid. I use a pencil because I had read that dark markings might cause a duck to peck at the egg. Don't know if that is true. With one team, I had to use my bedding fork to gently lift them off the eggs.
Good luck.