I think you are trying to apply logic to that which the creators didn’t expect you too.
Despite all, I’m goin with Regina (in story) only supposed to be around 7-10 years at the most older than Snow.
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"I could have the giant duck as my steed!" --Daniel Radcliffe
Keeper Of Tamara's Taser , Jafar's Staff, Kitsis’s Glasses , Ariel’s Tail, Dopey's Hat , Peter Pan’s Shadow, Outfit, & Pied Cloak,Red Queen's Castle, White Rabbit's Power To World Hop, Zelena's BroomStick, & ALL MAGIC