Mr Reid died a widower and had no children of his own, and in the months since his death an almighty legal battle over his fortune has broken out between more than half a dozen people – including his much younger niece and lover Peta Roberts.

Court documents reveal allegations of testamentary documents being signed in "suspicious circumstances" amid "undue influence" by one of the executors and claims Mr Reid was too impaired by dementia to know what he was doing.

A will made in 2000 is the first link in a chain of 22 other potentially testamentary documents executed (or not) with varying degrees of formality between 2001 and 2014.

Ms Roberts is Mr Reid's niece by marriage – her father's sister Victoria (nee Moses) was his wife. She died in 1998.

Ms Roberts told the NSW Supreme Court Mr Reid "made an advance towards her" at her aunt's wake. Despite the 45-year age difference, Ms Roberts and Mr Reid began an "intimate relationship which continued for many years". Ms Roberts, who lives on a 28-hectare hobby farm in Tasmania, would fly to Sydney at his expense, and eventually moved in to his Wolseley Road, Point Piper apartment.

By 2012, Ms Roberts was flying to Sydney twice a week and receiving $3000 cash each visit. He paid for her four daughters' education at Launceston Grammar School at a cost of $50,000 a year. In an affidavit she said between 2001 and 2011 Mr Reid had given her about $1.2 million and paid for everything she required, including the running costs of her farm.

She said they attended many social occasions together, she organised his 90th and 100th birthday celebrations, and she was "frequently assumed by others to be Mr Reid's wife".

Ms Roberts says she organised, and when in Sydney supervised, Mr Reid's round-the-clock nursing care, which he needed from about 2007 as his Alzheimer's disease progressed.

Six weeks after Mr Reid's death in August last year, Ms Roberts asked the court to order his executors to give her $150,000 to meet her urgent expenses, including $30,000 owed to her Tasmanian solicitors over a dispute with her former de facto husband over the farm.

She said at age 55 she was unemployed, had no savings, no particular qualifications and has Parkinson's disease. She has monthly liabilities and expenses of between $35,000 and $40,000, which Mr Reid had been meeting entirely.

Justice Francois Kunc​ made an interim distribution of $150,000, finding Ms Roberts was "completely financially dependant upon Mr Reid's extraordinary largesse" and "undoubtedly a beneficiary of the estate".

In the months since, a variety of claims have been made on the estate amid allegations Mr Reid was not of sound mind when he executed various wills, codicils and "statements of wishes" between January 2000 and July 2014.

Court documents show Mr Reid executed at least 12 codicils to his January 2000 will. He also wrote several documents titled "Statement of Wishes of Peter M. Reid".

These documents covered cash bequests to various people, artworks by Charles Blackman and Sidney Nolan, the appointments of directors and their annual fees for his private company VanReid​ Industries.

One of the estate's executors, Philip Palmer, has asked the court to order probate of the will and incorporate the 12 codicils and three "statement of wishes".

The first defendant, Rupert Moses, who is also an executor, has filed a cross-claim. He claims Mr Reid was aged between 85 and 99 at the time the documents were signed and suffered from dementia. Further, he says some of the documents were signed in "suspicious circumstances" and were prepared by Mr Palmer, who receives significant benefit from the estate.

The second to sixth defendants have filed a caveat against the make of a grant of probate of the will. The second defendant, Alexandra Bradley, a friend of Mr Reid who held power of attorney for him, says the first nine codicils are valid but the 10th to 12th are not because Mr Reid lacked capacity due to his dementia from February 2011.

The third to sixth defendants deny validity of the January 2000 will and all the subsequent alterations. They claim the correct will was one made in 1997.

Charles, Andrew, Annabelle​ and Rupert Reid claim Mr Palmer "took advantage" of Mr Reid's age and declining cognitive state "such that the deceased was not a free agent" and the 2000 will and amendments "were not of his own volition".

But Mr Palmer says the 1997 will was revoked by the one made in 2000.

Mr Reid was a director of Packer family company Consolidated Press Holdings from 1960 to 1993. He lived in two amalgamated apartments in an art deco building in Australia's wealthiest street.

His assets included real estate in Surfers Paradise, $6 million worth of NAB shares, artworks and antiques, and cash at bank of $215,000. He allegedly gave Ms Roberts the lifetime right to live in his Point Piper apartment, unless she remarried.

Justice Kunc said there will be "serious questions" as to whether some of the documents should be admitted to probate. There is also a dispute as to whether Ms Roberts has the right to rent out the Wolseley Road apartment while she lives in Tasmania.

The matter will return to court on Tuesday.