LOL...my last batch went to the coop at just over a week old. In with chicks in the grow-out pen for another week & then in with my 2 older Mallard drakes (about 2 1/2 months old now, about 6 weeks older than the "babies") I got tired of the mess in the brooder & since there were 4 of them & temps were staying well above 50 at all times I knew they would be fine in with the chicks.I never fed wet food to my duckling either.
Just make sure they have plenty of water. Talking about this brings back memories of how messy ducks are compared to chicks. Mine used to take big beakfulls of food, then run over to the drinker, and drop it in, mix it all about, then scoop it up, shake their heads, splattering the walls and floor with slimy food! Then they would do it again and again as fast as they cold, back and forth.
Finally they would love to stamp it all about in the brooder, lay in the mess, and rub it all over their feathers before going to sleep. Yuck! Now I let my ducks raise their own ducklings on the pond......much easier for me!