The Duck Tales 1997 and Duck Tales 2017 shows happen in alternate universes to Donald Duck and Uncle Scrooge comic books which happen in an alternate universe to Donald Duck and Uncle Scrooge cartoons.
I expect that many of the Donald Duck and Uncle Scrooge comic books licensed by Disney and created in many different countries and many different decades also happen in alternate universes to one another. And I guess that many Duck cartoons happen in alternate universes to one another.
For example, Comic book artist and writer Don Rosa wrote somewhere on the internet about how he tried to stay totally consistent with Carl Barks's stories, but did consciously change a very few details for a reasons which seemed valid to him. And some European Uncle Scrooge conic book lines are much more different from Don Rosa's, by giving Uncle Scrooge a brother, Gideon McDuck.
Gideon McDuck (Gedeone de' Paperoni in original Italian) is Scrooge McDuck's moralistic brother, and is a recurring character in Italian comic stories; in those stories, Gideon is the editor of the newspaper "The County Conscience", the most credible newspaper in Duckburg. The newspaper is originally known as "Il Grillo Parlante", which is the Italian name of the Pinocchio character The Talking Cricket and its Disney version Jiminy Cricket; a statue of Jiminy is therefore present in Gideon's office. Gideon also has an antagonistic relationship with his brother Scrooge.
The character was created by Romano Scarpa, and first appeared in the story "Paperino e i gamberi in salmì" (1956). The character's debut story is the only one that was printed in the United States, as it was published in 2015 under the title "Shellfish Motives".
Gideon's existence is inconsistent with a statement made in Carl Barks's "The Old Castle's Secret". In this story, Scrooge states that he is the last of the Clan McDuck, which would mean that he couldn't have a living sibling. However, Gideon is not the only living relative of Scrooge to carry the surname "McDuck", and therefore cause the same inconsistency with Barks's story; others include his sister Matilda and first cousin Douglas. In the American translation of "Shellfish Motives" Gideon is said to be younger than Scrooge, while the original version doesn't specify which one of them is younger.
Scrooge has only two siblings, Matilda McDuck and Hortense McDuck, according to Carl Barks and Don Rosa. Acording to Barks, Hortense married Quackmore Duke and was the mother of Donald Duck and Thelma Duck, who was the mother of Huey, Dewie, and Louie. Don Rosa makes Hortense and Quackmore the parents of the twins Donald and Della, born in 1920, and Della is the mother of mother of Huey, Dewie, and Louie.
The ages of the younger generations of Duck family members is an important clue to when various alternate universes diverged from each other.
As a child, reading Carl Barks comics, I was amazed at how long ago Uncle Scrooge had adventures according to various brief mentions. I was amazed that Scrooge could still be alive at his age. Don Rosa changed a few of the dates of Scrooge's earliest adventures to make Scrooge merely a member of my great grandparents' generation instead of much older.
Don Rosa wrote a series of comic books called The Life and Times of Scrooge McDuck giving the biography of Scrooge from an adorable child to the bitter old miser he was when first introduced in "Christmas at Bear Mountain" in 1947. Rosa made Scrooge born in 1867, Matilda McDuck in 1871, and Hortense McDuck in 1876, and Hortense's twins Donald and Della born in 1920, when their mother was 44.
In Duck Tales 2017, the episode "The Other Bin of Scrooge McDuck!", July 21, 2018, Webbby Vanderquack takes a hard bound book from a shelf, titled The Life and Times of Scrooge McDuck, and reads to Lena that Scrooge was born in Scotland in 1867, so the Don Rosa stories and Duck Tales 2017 should happen in universes which were the same in 1867 and in 1877 when Scrooge got his number one dime, and which diverge some time after 1877.
Huey, Dewey, and Louie Duck were the idea of Al Taliaferro, the artist for the Silly Symphony comic strip, which featured Donald Duck. The Walt Disney Productions Story Dept. on February 5, 1937, sent Taliaferro a memo recognizing him as the source of the idea for the planned short, Donald's Nephews. The nephews debuted in Taliaferro's comic strip, which by this time had been renamed Donald Duck, on Sunday, October 17, 1937, beating the theatrical release of Donald's Nephews by almost six months.
Huey, Dewey, and Louie Duck are the sons of Donald's sister Della Duck; in Donald's Nephews, their mother is instead named Dumbella. In the original theatrical shorts, they were originally sent to visit Donald for only one day; in the comics, the three were sent to stay with Donald on a temporary basis, until their father came back from the hospital (the boys ended up sending him there after a practical joke of putting firecrackers under his chair). In both the comics and animated shorts, the boys' parents were never heard from or mentioned again after these instances, with the boys ending up permanently living with Donald. All four of them live in the fictional city of Duckburg, in the fictional state of Calisota.
Huey, Dewey, and Louie
So in the theatrical cartoons Huey, Dewey, and Louie were probably born in the early 1930s, which would make their mother an early teenage mother unless she was born earlier than Don Rosa said.
So the early cartoons and comic strips in the 1930s with Huey, Dewey, and Louie imply that Donald and their mother (whatever her name was) were born before 1920 when Don Rosa said they were, thus making the point of divergence between them years before 1920.
In the Carl Barks comic books of 1943 to 1967, Huey, Dewey, and Louie were about the same age as in the 1930s cartoons, and so must have been born years later than those boys, maybe around 1940 - and they didn't grow older even in stories published in the 1960s.
In Duck Tales 1987, which was more or less set in a contemporary setting, Donald seemed reasonably young and so probably born decades after 1920, and Huey, Dewey, and Louie looked like little boys born in the late 1970s and so over thirty years younger than the Barks-Rose versions and over 40 years younger than the 1930s comic strip and movie cartoon versions.
Duck Tales 2017 is set in the 21st century, with the first season probably including the 10th birthday of Huey, Dewey, and Louie.
See: Duck Tales Chronology
In "The Secret(s) of Castle McDuck!" August 4, 2018, Huey, Dewey, and louie find a paper dated April 15, in an incomplete year number starting with 20. They say that was the week that they hatched, but "The Last Crash of the Sunchaser!" August 11, 2018, shows that they must have hatched after April 15, showing that they hatched between April 15 and April 22 of that year in the 21st century.
So in Duck Tales 2017, Huey, Dewey, and Louie were hatched sometime between 2000 and 2099, 80 to 179 years after their mother Della Duck was born in 1920 according to Don Rosa, and 124 to 223 years after their mother's mother Hortense McDuck was born according to Don Rosa. Since Scrooge was born in 1867 in Duck Tales, it would be hard to make his sister Hortense born many decades after the 1876 date Don Rosa gave her.
This implies that in Duck Tales 2017 duck generations, especially female duck generations, can be much longer than human female generations.
But since Duck Tales 2017 has many fantasy and science fiction plot elements, members of the McDuck family could experience magical or scientific events that cause them to be much younger than the amount of time which passed since they were born.
So Fergus and Downey McDuck could have had Hortense McDuck many decades after Scrooge was born in 1867. Hortense could have been very old by human standards when she gave birth to Donald and Della many decades after 1920. Della could have been very old by the time Huey, Dewey,and Louie hatched.
Or maybe some combination of the above.
And perhaps in Duck Tales 2017 the type of care which duck eggs receive after being laid determines how many months, years, decades, or centuries it takes them to hatch.
"The First Adventure!", November 16, 2020, opens in the 1960s, when two foul fowls found the foul organization F.O.W.L. The rest of the episode happens decades later, possibly in the 1990s, when Scooge uses a bulky old cell phone. Donald and Della Duck are children in this era. Their mother Hortense sends them to Scrooge while their unnamed father is in the hospital after Donald and Della played the same prank on him as Huey, Dewey, and Louie played on their father in their first comic strip in 1937.
And I have to wonder whether the fathers died from the pranks in both cases and the mothers refused to have anything to do with their children as a result.
Anyway, that shows that Della Duck was still a kid in the late 20th century in this timeline, and was probably born about 60 years after she was born in the alternate universe of Don Rosa stories. So Della could have been the mother of Huey, Dewey, and Louie at a normal age if they were born early in the 21st century. So it was probably Hortense and Quackmore and/or Fergus and Downey who were much older parents in this timeline.
In "The Golden Lagoon of White Agony Plains!", June 23, 2018, Scrooge offers a partial explanation for his survival, while "The Secret(s) of Castle McDuck!" gives an explanation for the survival of other members of the McDuck family.
Comparing "The Secret(s) of Castle McDuck!" with The Life and Times of Scrooge McDuck indicates that the two alternate universes diverged in the 1890s.
And see: Is Scrooge McDuck immortal?