Can I put day old ducklings under a hen?

[LapisLazuli]

I have a broody hen who is sitting on a clutch of infertile eggs she is on her 3rd week. Can I put day old ducklings under her?

 

[Chicalina]

I would do it at night, in the dark, perhaps one at a time over a couple of hours if you can. Some might do it all at once.

Watch carefully.