Why exactly does Donald stay with Daisy? She leaves Donald for Gladstone whenever she damn well feels like it, and it's not like Donald doesn't have better options. (Those "better options" including Xadhoom and Kay K. The former of whom he's flirted far more with than Daisy....)
If you think too much about Don Rosa's Arc Welding work, you have to conclude that everyone's parents are dead.
Not much fridge: The Life and Times of Scrooge McDuck showed Scrooge's father's corpse... On the other hand, Matilda McDuck is still alive and well, so Hortense and Della could still be around.
Furthermore, Don Rosa usually implies that his "Present Day" stories are actually set during the heydays of Carl Barks' classic stories (thus mostly during The Fifties), which means that as of right now, most characters should be either really old (e.g. Donald and even HD&L) or most probably already dead (e.g. Grandma Duck and Scrooge himself)!