In the 10 years since Amy Winehouse's death, a handful of her unreleased songs have been uncovered for the posthumous albums Lioness and Amy.
But most of the material she recorded is presumed to be missing, after label boss David Joseph destroyed her demos to prevent them being exploited.
"It was a moral thing," he told Billboard in 2015.
Letting other people finish her work "would never happen on my watch," he added.
"It now can't happen on anyone else's."
While many critics applauded his desire to protect Amy's legacy, her father has a different view.
"He's an idiot," Mitch Winehouse told the BBC, adding that "of course" he wanted fans to hear her unreleased songs.