I hesitate to throw this out there, because they are just little ducklings, but I believe some people put a dab of Preparation H on swollen vents. I have also heard of putting honey on the vent.
Take a look at this, especially post number 22 - it refers to Preparation H, honey, and vaseline.
Poor babies. Poor duck parents.
Take a look at this, especially post number 22 - it refers to Preparation H, honey, and vaseline.
Poor babies. Poor duck parents.
Hens go broody when you don’t want them to… and won’t go broody when you do. 

