Chickens are a different story, but unless the ducks are being kept with other fowl, I've never quarantined any of the ones I have gotten.
In reality, most people that say they quarantine new birds aren't actually doing it properly in the first place. Viruses are highly contagious, so can be carried by wind, minuscule amounts of dust, other birds, mice, etc. Therefore to correctly prevent them from spreading, they require strict precautions. Strict enough most people aren't able to properly follow them.
Ok, I do know the family I’m getting them from. They got them around Easter and are just looking for a better home for them. They purchased them from the same place my original 3 ducks came from. Thank you