Looks like you are now a beekeeper
If you are going to put chicks and ducklings in the same brooder, my recommendation is to have all of them on wire rather than in a flat bottom tub. The ducks like to splash the water out of the waterers and the chicks get wet and too cold when there isn't a way for the water to drain off the living area. As for putting them in the same yard, I found it was very difficult to keep the waterer clean when ducks had access to it. They dip their beak to clean off their nostrils and seem to leave mud behind in the waterer.
Yes I have noticed that. I have to change the paper and water at least a few times a day. They aren't brooding together, but I kind of wanted to put them in the same yard. I decided it will be just as easy to build a chicken wire T- post yard for them. I have a doghouse that my last duck lived in. I think they'll be fine in there, if I put a top on it to keep predators out. How long do ducks usually brood?