Ursula K. Le Guin: Tales from Earthsea or Gedo Senki

She basically ignored the wisdom of her own advice. A corollary of "don't blame the original author" is "it's not your story once the film company has the contract signed"

"Saving Mr Banks" is this for PL Travers and Mary Poppins.

Tolkien estate, Philip K Dick estate, CS Lewis estate....