I separate my broodies and babies into a large dog kennel for a couple of days to let them bond. They have their own food and water. After a couple of days I open the kennel door and let mom take the babies out when she is ready. The kennel is in the barn in a separate area from the coop but also has access outside. The broodies take the babies outside when they are ready. I have done the same process with the kennels in the coop before and it worked just fine. I moved them out because they were taking up too much room and it was easier to provide water in the barn away from the adult ducks.
Though there are some broodies I've had that don't take to being moved and I have lost chicks in the process. But they also seem to have trouble bonding to the chicks in general. Some are decent at sitting but not cut out for raising young.
I currently have two broody chicken hens that have several chicks but also a single duckling each. The ducklings follow 'mom' around just like the others. So far I haven't had any trouble with the other chickens or ducks, just some turkeys that are now gone.