Winter, 14, is one of the stars of the ABC sitcom "Modern Family."
TMZ cited court sources it did not name as saying Ariel's adult sister Shanelle Workman was awarded temporary custody of the actress following a guardianship hearing last month.
A judge ordered the sisters' mother, Crystal Workman, to stay 100 yards away from Ariel while the matter is being investigated, the celebrity news web site said Wednesday.
Shanelle, whose age was not reported, suffered the same alleged abuse as Ariel and was placed in foster care for more than two years two decades ago. She never returned to her mother, TMZ said.
The family is due back in court Nov. 20.