Lawyers for Gina Rinehart's youngest daughter Ginia claim they have been "blindsided" by a last-minute move by her two estranged siblings to switch places in the battle for control over the contentious family trust.
For months, Australia's most famous family feud was shaping as a contest of credibility between the mining magnate, who had refused to step down from the position of trustee, and her only son John Hancock, who had put himself forward to replace her.
But early yesterday, with just over an hour to go before day two of the civil trial against Australia's richest person was due to begin in the NSW Supreme Court, Mr Hancock announced he would withdraw.
His sister Bianca Rinehart had agreed to nominate in his place.
"I made the decision last night to ask Bianca to nominate as replacement trustee," Mr Hancock told _The West Australian _yesterday.
"I also decided to stand down as replacement, in the interests of family harmony, and support Bianca's nomination."
The new twist in the long-running row caught Mrs Rinehart's legal team off guard.
Lawyers for Mrs Rinehart and Ginia had for weeks foreshadowed "unpleasant" evidence that would be presented against Mr Hancock to argue against his move to take control of the trust.
"Now, at 9am on day two of the trial, Bianca is put forward and we are simply blindsided," Ginia's lawyer Richard McHugh told the court.
"If the plaintiffs wanted to have Bianca as trustee, they should have said so months ago."
He said that if Bianca were to be accepted as a nominee, her sister would need time to gather evidence against her.
The nominee switch was the latest in a series of eleventh-hour twists that have reshaped the battleground on which the long-awaited court case will be fought.
Last week, Mrs Rinehart agreed to do what her children had demanded and step down as head of the family trust, a decision her lawyers said negated the need for a trial.
It also meant evidence against her prepared by Mr Hancock and Bianca, who had accused her of "gross misconduct" and dishonesty, would not be heard by the court.
Yesterday, as her lawyers were getting ready to argue against the suitability of her son to replace her, he stepped out of the race.
The confusion further delayed opening arguments on the second day of the long-awaited trial.
Late yesterday, with the trustee issue still undecided, John and Bianca won access to dozens more documents surrounding the trust and a 2006 change made by their mother to a constitution governing the affairs of the trust.
This week's civil trial comes more than two years after John, Bianca and their sister Hope Welker launched legal action against their mother, claiming she misled them over the implications of vesting the family trust.
They demanded that she be removed as trustee because of alleged "gross misconduct".
Their central claim revolved around their mother's surprise move in September 2011 to put back the imminent vesting date of the family trust by more than half a century, claiming they would be bankrupted by capital gains tax if they refused.
Hope dropped out of the fight amid financial trouble this year.
Ginia has sided with her mother throughout the battle.
Mrs Rinehart has continually denied any allegations of misconduct and dishonesty and has maintained she has always acted in her children's best interests. The trial will continue in the NSW Supreme Court today.