Victoria Rockefeller (nee Lawson), who hails from Waikouaiti, has been granted the right to her husband's $14.6 million fortune by the Supreme Court after she declared he had no other genuine domestic partners.
The estate includes a $1.7 million historic home in Hobart and a beach-side home in South Australia.
Mrs Rockefeller's lawyer, David Hughes, has said he would be getting advice from New Zealand, where at least $3.5 million was owed to Mr Rockefeller by private companies.
The 51-year-old Mr Rockefeller - who was known to be a private and quiet man - led a secret life and was involved in an underground swingers' network in Melbourne.
He was bashed to death when he turned up to a swinger couple's home without a partner, and his body was later dismembered and burnt in the backyard of a second property.
He did not leave a will.
An affidavit, signed by Mrs Rockefeller, who met her husband in the 1980s, said she was her husband's sole domestic partner.
"The deceased did not leave a person who at the time of his death was a domestic partner living with the deceased as a couple on a genuine domestic basis - irrespective of gender - save and except for myself, his widow."
However, she might have a fight on her hands if a woman claiming to be her husband's long-time mistress makes a claim to the estate in the Supreme Court.
The woman, known only as "Liza", says she had been having an affair with the multimillionaire for 27 years and that they had talked about getting married.
She has six months to make a claim.
This week, Mrs Rockefeller was granted letters of administration, seven months after she made an application.
She would be entitled to her husband's personal effects, one third of his estate plus $100,000; while two-thirds of the estate would go to the couple's two children.
Mr Rockefeller was a well-known businessman on both sides of the Tasman, having been the chief financial officer for Brierley Investments between 1992 and 2000 in New Zealand, and was a director of Genesis Research.
He also bought a six-level block in Petone, for $3.5 million, and the family also owned a holiday house in Karitane, formerly occupied by Plunket founder Sir Truby King.
Mr Rockefeller was a friend of Prime Minister John Key.
