If you want a good layer duck that will also go broody, Welsh Harlequins are a good breed. Buff ducks will also go broody. They don't lay quite as well, but are meatier. Both are considered dual purpose breeds.
If a breed isn't known for going broody, it basically means your odds are low, but as you see, it is possible. I had a runner duck hatch out a clutch of 12 ducklings. Runners are not known for their brooding ability, but the crazy thing did a great job, she was very protective and didn't lose a...