This is what my Scovie girls do, they will lay an egg a day then when they feel they have enough be it 6 or 20 then they will start to sit, if you want one to go broody leave the eggs, you might want to mark them so when you feel she has enough, [you know how many ducklings you can accommodate] then you take out the ones you don't want her to sit, they won't start developing till she begins to sit round the clock. she may start out sitting at night and leave them covered during the day time but when she makes her mind up she'll be dedicated 24/7 with only short trips off to eat and bath. very important for her to have access to water for keeping the humidity level good in the nest .
