A lot of viewers and critics were not fond of
"Although her voice is amazing, she doesn't have acting experience," Derbyshire said. "It's just the overall image, she's a country star, she won 'American Idol,' she's very public in kind of a tabloid way."
So who would the Von Trapp family have preferred?
"Here's someone who just won an Oscar for a similar situation," the 28-year-old Derbyshire said of Hathaway. "She was able to act and sing."
In a strange coincidence, Hathaway co-starred with Julie Andrews, who played Maria in the 1965 film version of "The Sound of Music," in the two "Princess Diaries" films.
Andrews gave her blessing to Underwood while speaking with Zap2It earlier this year, saying, "I do hope it works for Carrie, because she's lovely and I'm a fan. I wish her well."
Derbyshire isn't the first Von Trapp to criticize Underwood's casting publicly. A year ago when the production was first announced, Francoise von Trapp wrote a blog post raising reservations about Underwood.
"One thing is for sure, the news has created quite a stir on Facebook among the von Trapp cousins of several generations," she wrote. "While opinions are mixed, it seems most of us don't think Carrie can quite fill Dame Julie Andrews' dirndl; or