How old are Huey, Dewey, and Louie in Duck Tales (2017)?

In "The Other Bin of Scrooge McDuck!" Webby reads aloud from a book titled "The Life and Times of Scrooge McDuck" that Scrooge McDuck was born in Scotland in 1867, just like Scrooge McDuck was in Don Rosa's classic comic series The Life and Times of Scrooge McDuck.

So the birth year of Scrooge McDuck should be the same in Duck Tales (2017) as in the comic book series The Life and Times of Scrooge McDuck. But they later diverged into alternate universes, where Huey, Dewey, and Louie were born decades later in Duck Tales (1987) and later still in Duck Tales (2017).

In the first episode "Woo-oo!" and the last episode of the first season "The Shadow War!" it is said that Scrooge has been estranged from other members of his family for ten years.

Several episodes say that Scrooge and Donald broke with each other because of the fate of Della Duck, the mother of the boys and sister of Donald, in the "Spear of Selene" incident.

The episode "The Impossible Summit of Mount Neverrest!" happens around Christmas. So most or all later episodes must happen after New Years Day of the next year after the year of "Woo-oo!" and "The Impossible Summit of Mount Neverrest!". The problem is deciding which episodes are after "The Impossible Summit of Mount Neverrest!", Should the episodes be put in order of their broadcast dates or the order of their production numbers?

Like a television season in the USA, or a school year in the USA, the fictional dates of episodes in the first season of Duck Tales (2017) begin during one calendar year and continue into the next calendar year.

Since "McMystery at McDuck Manor!" was both produced and broadcast after "The Impossible Summit of Mount Neverrest!", it should happen in the next year after "The Impossible Summit of Mount Neverrest!". Scrooge's birthday is celebrated during "McMystery at McDuck Manor!", which indicates that in Duck Tales (2017) Scrooge was born in the first half of 1867 instead of the second half of 1867.

In "The Secret(s) of Castle McDuck!", which was the third to the last episode produced, and the third to the last episode aired in the first season, Scrooge, Launchpad, and the boys visit Castle McDuck in Scotland. Castle McDuck is surrounded by mist that only clears for a short time, enabling the castle to be reached, once every five years, apparently due to Scrooge buying cheap stones to rebuild the castle long ago, stones that turned out to be mystical druid stones.

In a hunt for treasure, the boys follow clues on a note leading to a bag containing Donald Duck's hat, hidden by Della Duck as a prank on her brother Donald. So Donald and Della were at Castle McDuck when she pulled a prank on Donald, and Castle McDuck can only be visited for a brief period every five years.

So Della and Donald must have been at Castle McDuck almost exactly five years before "The Secret(s) of Castle McDuck!", or else almost exactly ten years before, or else almost exactly fifteen years before, etc., etc. Furthermore, the paper with the clues has a drawing of the Spear of Selene on the back. Since Della Duck disappeared in the Spear of Selene incident about ten years before, she cannot have been at Castle McDuck playing pranks on Donald less than ten years before "The Secret(s) of Castle McDuck!" - unless she was a playful ghost.

And the paper also has a date. The date is April 15, 20__, the last two numbers covered by a thumb. The boys say that was the week they were born. So Della and Donald Duck were in Castle McDuck less than a week or less than seven days before Huey, Dewey, and Louie were born. So the boys hatched sometime between April 15 and April 22, in a year that was sometime between 2000 and 2099.

The next episode, "The Last Crash of the Sunchaser!" should happen soon after "The Secret(s) of Castle McDuck!". Scrooge says that "Woo-oo!" happened about six months before, and thus probably about October of the previous year, and indicating that Scrooge's birthday is probably sometime during January to April - at least in the alternate universe of Duck Tales (2017).

In a narration of the Spear of Selene incident flashbacks show Donald leaving Scrooge after Della is lost. And Donald is shown pushing a baby carriage with three eggs in it. Thus Donald and Della must have been at Castle McDuck, returned to Duckburg, and then the Spear of Selene incident happened and Donald left Scrooge, and then Huey, Dewey, and Louie hatched, all within the period of April 15 to 22.

At the end of "The Last Crash of the Sunchaser!" Donald and Huey, Dewey, and Louie all leave Scrooge and McDuck Manor, followed by Mrs. Beakley, Webby, and even the ghost of the butler Duckworth.

In the next episode "The Shadow War" Scrooge says that his housekeeping staff left three days ago.

Thus Huey, Dewey, and Louie seem to have been about nine years and six months old in "Woo-oo!" and about ten years and a few weeks old in "The Shadow War!".