Duck family (Disney)
Huey, Dewey, and Louie Duck are Donald's three nephews and identical triplet sons of Della Duck and an unnamed father.
Ludwig Von Drake
In the story "The Family Tree Spree", Donald scares of seeing Ludwig's specs on the floor and thinks about them as "Uncle Ludwig's specs". In the end of this same story, it's revealed that Ludwig also appears in Donald's paternal family tree, wherein he and Donald both have an ancestor called Colombust Duck. Since Humperdink Duck (aka Grandpa Duck), Grandma Duck's deceased husband, was probably almost contemporary with Ludwig Von Drake, it's possible to consider they were half-brothers, Donald being thus Ludwig's grandnephew. Ludwig revealed in "Blown Up Genius" that he came from a long line of glass blowers. In "The Big Payoff", it's revealed that he spent many months living in Donald's house since his arrival in Duckburg. Ludwig wins a TV chess challenge in this comic story, making Donald exclaim, "Yippee! He did it! Now he can pay all he's owed us (he and his nephews) for these many months!". According to the story "The Jewels of Skull Rock", Ludwig spent six months in Donald's house.