I think its the
Vague Age that's confusing everyone. There's nothing to suggest that Derpy is that much older than Sparkler... or any background pony that's not a filly, really. And there isn't a "teenage" pony model (Young Fluttershy might count, but then again that's only a year older than Young Pinkie).
Because of this, some fans are now saying Derpy is too young to have
two daughters, despite the fact we don't know the ages of either Derpy or Sparkler (or Dinky for that matter) and ponies probably age differently from humans
anyway.
Background ponies are terribly inconsistent anyways. Sparkler and the other Big Sisters were in the stands watching themselves... not unlike the Young Flyers Competition.
All Dinky/Sparkler thing really does is add fuel for Dinky fanart not involving Derpy. I love Derp-mom, I added most of the Derp-mom pictures in the
Fanon Heartwarming section, but I want to see Dinky interact with other ponies you know. That's what I liked about her in "Luna Eclipsed", she was hanging out with the Cutie Mark Crusaders!
Personally I'm subscribing to the
half-sisters
◊ theory with Ponet being the shared father. He's a purple unicorn! It fits!
EDIT: Ninja'd so hard.
Conservation of Ninjutsu does not apply to me.
edited 6th Nov '11 8:15:30 AM by Calnos