Are you wanting duckings or older but still young ducks? Asking because young ducklings will have to be brooded until feathers are grown in. But older ducklings that are feathered in can go into the chicken coop you'll just have to set it up where they can be separated some how so the chickens get used to them. Birds can be pretty rough on new flock members and chickens can be brutal. But if you go by introductions slowly maybe a week maybe more depending on the temperament of your chickens. You could use a large dog crate inside the coop until they are all accepting and if you use a run separate it so chickens are on one side ducks on the other, then once they have met that way try bringing them all together for some treats where they are busy eating and not so much interested in each other. It takes time but it does work.
My Runners and Buffs and my goose share one of my coops with my chickens and they all do great together. Only thing I changed in the coop was to put up poop boards under the roosts to keep the ducks from being pooped on overnight.
