Bill died in 1997, Dorthy in 2016.
When Bill died, he left half his estate to the couple's youngest daughter, Helen, while the oldest daughter, Dale, received nothing - on the basis that she had been able to purchase the family farm, Hazeldale, on favourable terms, while he was alive.
Dale threatened legal action, but ultimately did not pursue it. She again threatened then dropped legal action after Dorothy's death, when she was left $30,000.
However, the mother's will did see the youngest daughter, Helen, take action under the Family Protection Act 1955.
"Helen received substantially less than her two middle sisters under her late mother's will," Justice Rachel Dunningham wrote in her judgment, filed on March 20.
"At the date of her mother's death, Helen's share of the estate of $1,972,575 was $405,727, whereas the share that each of the two middle sisters would receive was $743,227.
"Helen says that this disparity cannot be accounted for by gifts made to her during her parents' lifetime. She claims, in the circumstances, that her mother has breached her moral duty to treat her equally with her sisters."
An accountant who gave evidence for Helen Walker said that allowing for inflation and changes to property values, the three younger sisters had received $6,240,387 in benefits during their lifetime and under their parents' wills. Had this been distributed fairly, each of them would have received $2,080,129. Because Helen only received $1,733,509 in benefits, the accountant calculated she has been disadvantaged by approximately $346,620."
Justice Dunningham accepted the calculations, but dismissed Helen Walker's claim.
"While the disparity she claims there was with her sisters, in dollar terms, was a meaningful sum, it fell well short of a failure to provide for her and recognise her as a family member," Justice Dunningham said in her judgment.