@Dehpi , while this is an official tree and the one pictured in the original post is not, it is not "the correct family tree" — merely the famous one. Don Rosa has created several other drafts of this same tree, including an early one where Daisy is depicted as Mr Duck's sister. Johannes A. Grote's exclusive German tree says the same thing
And I mean, the version you posted doesn't deny that Daisy is the triplets' aunt, it simply doesn't positively say so.
YAYYY! Time to show off my favourite part of the duck family- so, Della married daisies brother in law who is referred to as mr duck, making daisy the triplets aunt in law, and daisy Donald’s sister in law.
Did anyone ever see the(really old) one where Donald want to propose and meets the parents. The place was a train wreck and the three boys (I am assuming Huey duey and Louie)’come running by him. I always assumed those were her kids and the reason they called him uncle was because that’s what they call every “strange man” she brings home. In the same cartoon Donald and daisy are under a tree and there are many couples initials crossed out. I paused it to see if 3 of those sets were were her to support it but no luck. Any thoughts