AceShowbiz - Sadie Frost has been left reeling after a woman contacted her alleging she is the star's half-sister, according to a U.K. report. The British actress opened up about her father David Vaughan's womanizing in her new autobiography, "Crazy Days".

And the revelations prompted an unnamed woman from Manchester, north England to contact Frost as she thinks Vaughn may be her father. A source tells Britain's Daily Mirror, "Sadie is shocked. She knew her father was pretty wild but she thought she knew all of his children."

"At the back of her mind she thinks there may be even more." Frost will reportedly undergo a DNA test later this September to establish if the mystery woman is a relative.