Last week my broody hens had some babies. Some of the hatch were ducklings. The hens soon pushed the ducklings out the nests keeping the chicks only. In the evening I heard the peeping I know so well, cold ducklings. My brooder box was ready and they are now in the house.
This week I heard a ruckus in the yard and a peeping of an unhappy chick. I see the hen with her brood and a tiny black and white Bantam chick with a bloody head and lots of noise all alone. It was attacked by other hen or another large bird. So into my pocket he went. I got back into the house, cleaned it off and put it in the brooder with the ducklings. After only a few hours it settled down and is with the ducklings. My husband holds the chick in his lap while the ducklings swim in the tub. I clean their cage while they swim. After a time the pile goes back into their cleaned brooder. Normally I stuff an orphan chick under a sleeping hen with chicks. Normally this works like a charm if they are about the same age. But sometimes a chick just can't keep up with the hen and the brood. So it becomes an orphan I raise. I then try to get 2 more chicks to raise with the orphan. This way they grow up together and stay together as teens/adults.
With ducklings same thing, but I take them outside in a temporary yard with an older foster female duck. This is after they outgrow the indoor brooder. Foster mom duck shows them how to follow, forage and go in a crate at night. After the ducklings are half grown (2 months) I release them with the foster mom duck. She will rejoin her flock with her "babies". It is more work but in the long run the foster duck system works. The older non laying foster mom duck has a job and the orphans get a ticket to join the flock.