Ah, I see. Well, that seems like quite the well-rounded theory! Not quite sure about “Diana Duck” as a name, though it has a nice ring to it. What with Daisy and Rosa, I think I'd like for the third sister to also have a flower-related name; thus, like AMJ's month-based names, such "name triads" would be reimagined as a family tradition.
Initially I actually wanted to call it Rosa because the ancestor she looks like is called Rosarossa (RedRose), but the obscure quote was too tempting for my nerd soul.
Yup, I'll go with Mabel looking older than she is because she's totally exhausted.
I was aware of the timeline issue BBJ raises, but thought we could fudge it believably. I'm the youngest in my family, and my parents were 38 when I was born. Oldest sibling is 15 years older than I. If Daisy's mother was 38 when she was born, then the mother would have been born around 1882, and could be 21 in the Invader scene. Anyway, we know that in general Rosa's timeline has his Ducks give birth at later ages than was typical for humans of the time.
Another option, if we really want to tie this couple to Daisy, is to have them be Daisy's grandparents. Perhaps Daisy's future father/mother is sleeping in the back of the wagon during this scene?