Her daughter Sarah Biasini told the AFP news agency that they were "scandalised" by the film 3 Days in Quiberon, which she said smears one of Europe's biggest postwar female stars.
The biopic turns on an interview given by the star of the Sisi trilogy, The Swimming Pool and What's New Pussycat? to the German magazine Stern over three days while staying at a spa resort in 1981, the year her son died in a freak accident.
But Biasini -- herself an actress -- said the film "contains multiple insinuations which are totally false", particularly that her mother, who died aged 43 in 1982, was an alcoholic.
"When you look back at all the directors and actors who worked with her, no one ever said that she had a drink problem," her daughter insisted.
The last months of Austrian-born Schneider's life were marked by tragedy after the death of her 14-year-old son David, who was impaled on a spiked gate at his grandparents' home.
The new film suggests the actress went to the Brittany spa in the hopes of curbing her dependency on drugs and drink after his death.
Her daughter, who was four when Schneider died, insisted her mother was there simply to recover and lose weight.
"She went to Quiberon every year to lose a few kilos like a lot of actresses. It was something she always did. It wasn't a detox centre, it was just a spa," Biasini said.
To suggest otherwise "is completely malicious. They wanted to smear her," she told AFP. "I want people to stop trying to make money on these lies."
Mystery still surrounds the death of Schneider, whom the French film idol Alain Delon later called the love of his life.
She is thought to have died of a heart attack after reportedly taking painkillers with wine, but the Paris coroner who investigated her death refused to order an autopsy.
The actress had been unwell after a kidney operation.
The director of 3 Days in Quiberon, Emily Atef, has admitted to fictionalising parts of the Stern interview for the film, which won seven prizes at the German Film Awards this year.
"I needed to have that licence from the real events to reach to a truth about the character," she said in notes for the film.