Contrary to popular belief, Scrooge doesn't just have the two sisters, he's got four more siblings. The names of Fergus McDuck's children, from oldest to youngest, are:
Evelyn. The oldest of all, and possibly the daughter of Fergus' first wife. Had already left home by the time Scrooge got the Number One Dime, and in the present day she's passed away and left Donald her cat.
Scrooge. We all know who he is.
Marley, Scrooge's TWIN BROTHER. Left home after failing a stinginess test before Scrooge even got his Number One Dime, and currently resides in an Arizona ranch looking for gold veins and gifting them to the needy. Scrooge apparently believed him dead for a long time, and while he now knows he's alive he refuses to admit his existence unless forced because the McDuck's stinginess is legendary even for Scotland and Scrooge is the stingiest of all.
Matilda, middle of the sisters. Married and divorced twice, first with one Goostave Gander (who would later go on and marry Donald's paternal aunt Daphne and have Gladstone. Yet another reason for Donald and Gladstone to not get along) and later Ludwig Von Drake (no known children, though Donald gets along with this uncle). Currently resides in the McDuck's old castle as the caretaker, as the result of Donald's plan to reconcile her with Scrooge.
Hortense, the youngest of the sisters and the LEGITIMATE McDucks. Donald's mom, and her legendary anger is the source of half of Donald's. Her whereabouts are currently unknown, though she's presumably with her husband Quackmore (the source of the other half of Donald's anger) - her final chronological appearance was in 1930, when she told her friend Dolly a softened version of why she and Matilda had just cut relations with Scrooge and that she and Quackmore were about to leave the city on a vacation to calm down and that in the meantime they'd be leaving the twins Donald and Della with Grandma Duck.
Gideon, oldest of the half brothers. Has a mixed relationship with Scrooge, seemingly because his older brother didn't consider him a REAL McDuck when they were raised together in Glasgow. Currently the most honest journalist in the world.
Rumpus McFowl: the youngest half brother, that Scrooge didn't know existed until well after he met Donald and sort of reconciled with Gideon. By then Scrooge had learned his lesson, and they do get along.
The immensity of Disney productions, everybody. So immense that Donald once got lured in the castle of a vampire pretending to be his recently dead uncle because Donald has too many uncles to remember them all and just figured out he had forgotten this one or didn't even know of him.
There's also the fact Dolly Duck was a cousin of Goostave Gander and a PHANTOM THIEF with the name of Dolly Paprika alongside her fiance John Lamont Quackett (AKA Fantomius, the Gentleman Thief), and the reason Donald knows that the journal of Fantomius (that would inspire Donald into becoming Paperinik the Devilish Avenger) doesn't minimize her role is that he personally knew them as a child.
Or just why there's three Elizabethan era CASTLES near Duckburg. Or Donald's great grandfather getting the Medal of Honor in the US Civil War for blowing up Fort Duckburg while a distant cousin of his was basically a Rhett Butler whose Rossella was a good person.
Or the fact José Carioca once casually admitted he practices BLACK MAGIC and we don't know exactly how he got the magic powers he immediately demonstrated. It's almost as mysterious as what happened to Della's husband (though we know what happened to her, she'll be back by the time her children are twenty and realize what relativistic speeds mean).
Genuinely the drama has me reaching for popcorn
