(Recasts with family to accept any award)
LOS ANGELES Feb 18 (Reuters) - Matilda Ledger, the three-year-old daughter of late Australian actor Heath Ledger, will be the eventual owner of an Oscar if he wins a statuette on Sunday, but his family will accept the award on his behalf.
The Academy of Motion Picture Arts and Sciences said on Wednesday it has decided if Ledger wins a rare posthumous Oscar for his performance as the villainous Joker in "The Dark Knight," Matilda would receive the Oscar after she turns 18.
Ledger, 28, who died last year of a prescription drug overdose, is widely expected to win the best supporting actor Oscar at the Feb. 22 Academy Awards in Hollywood after picking up virtually every other award in that category this season.
He would be only the second actor to receive an Oscar after death, following Peter Finch who won in 1976 for "Network", and his family will be on hand if he does win, travelling from the actor's home town of Perth in Western Australia for the ceremony.
"We have had Oscars awarded to a minor directly and Oscars awarded posthumously but generally there has been a spouse or an oldest child of legal age" to accept them, said Bruce Davis, executive director of the Academy.
"I don't think we have ever had a situation like this."
Australia's The Age newspaper said Ledger's family will accept the actor's hotly tipped Oscar if his posthumous award-winning streak continues.
His maniacal portrayal of the Joker has already won him best supporting actor at the BAFTAs, the Golden Globes and the Screen Actors Guild Awards.
The newspaper said his father Kim Ledger, mother Sally Bell and sister Kate Ledger will all walk the Hollywood red carpet ahead of the awards and accept a statuette on his behalf but they had not yet decided who would address the ceremony if he won.
Ledger's engagement to actress Michelle Williams, Matilda's mother, ended before his death and he was not previously married.
Matilda is too young to sign the winner's agreement, required of all nominees, which says the recipient will not sell his or her Oscar before offering it back to the Academy for $1.
Davis said that after discussions, Williams agreed she would hold any Oscar in trust for Matilda until her daughter turns 18. Matilda could then choose to keep the statuette or return it to the Academy.
"It was a new circumstance for us and we had to figure out what was fair and what would work," Davis said.
The Academy declined on Wednesday to say who would accept the Oscar at the podium on Ledger's behalf if he were to win.
At the Golden Globe awards, "Dark Knight" director Christopher Nolan accepted the trophy for Ledger and at the Screen Actors Guild honors, "Dark Knight" co-star Gary Oldman took the stage to handle the statuette and make a speech on Ledger's behalf.
His family in Australia have said they expect Matilda to eventually inherit those awards.
(Additional reporting by Belinda Goldsmith)