Alright let me just answer all your questions right now.

Because I already used Sweetie, there are no other Unicorn foals, and Apple Bloom reminds me a lot of Twilight.

Cast:
Sweetie Belle - Young P.T. Barnum
Apple Bloom - Young Charity Barnum
Rarity - P.T.
Twilight - Charity

And Twilight fits Charity because she's grown up in a life of riches and opportunity but gave it up to live with the ones she loves.

Or maybe I've been reading too much Enchanted Library... who knows.

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