Is Bianca Gina's bolt from the blue? Ginia and Gina Rinehart outside court. WHILE Ginia Rinehart is considered the prime contender to take over the family dynasty's trust from mother Gina, it's middle daughter Bianca who best fits their mother's list of requirements. The billionaire matriarch made the shock announcement on Tuesday that she no longer wanted to act as trustee to the fortune that has mounted since her late father Lang Hancock helped pioneer the Pilbara iron ore sector. The surprise backdown came days before the family's bitter legal battle was to go to trial. Through lawyers Corrs Chambers Westgarth, Gina Rinehart said her decision should end litigation with estranged son John Hancock, who is backed by Bianca in trying to remove their mother as controller of the trust and alleges she engaged in serious misconduct by withholding information about it from her children. The furore erupted in September 2011 when Ms Rinehart, Australia's wealthiest person, told her children the trust would not vest within days as previously arranged, when youngest daughter Ginia turned 25 - but in 2068, when John would be 92. He claimed his mother had wrongly told the children they would have faced a massive capital gains tax bill if she had stuck to the original vesting date. In August, she wrote an open letter to John and Bianca, saying she would be willing to appoint a co-trustee, but that olive branch failed and the pair continued to push for the disclosure of documents. And Ginia, the only one of the four children to side with Ms Rinehart, yesterday lost her bid to keep the battle out of the NSW Supreme Court next week through mediation. So as the drama unfolds in the public eye, who will emerge as the matriarch's replacement? Certainly not John, given he wouldn't fit her suitability criteria. She listed them in the backdown announcement, saying it was critical that the new trustee - or trustees - would be a lineal descendent. While he and Ginia obviously fit that bill, she could well be seen as a proxy for her mother. And in an apparent stab at John, Ms Rinehart went on to say her successor would not have "a history of wanting trust benefits applied disproportionately to their own benefit." He wrote to his mother when the dispute first erupted, offering to reach an arrangement independently of his sisters "who have always been treated better anyway." Gina Rinehart with her son John and daughter Ginia at the Telstra Business Women's Awards. She also stipulated her successor would "be willing to listen to advice from people experienced in the resources industry." Enter Bianca, who worked for Rio Tinto - even driving haul trucks - to get first-hand experience in the family trade. "She's got out there and rolled her sleeves up," a long-time observer of the family said. She's a very strong, if not wasted, talent. She understands mining. She could be the one. Gina Rhinehart's son, John Hancock. Picture: Michael Perini Source: The Daily Telegraph There's a possibility Bianca and her mother could reconcile, given Ms Rinehart already appears to have healed old wounds with her second youngest daughter, New York-based Hope Welker. Hope had joined John and Bianca's fight and reportedly knocked back a $300 million offer from their mother to settle despite being broke. But it emerged in March this year that she had pulled out of the stoush, telling her lawyers "the nature of the litigation is not something I am prepared to withstand personally." The next month - in a surprising twist worthy of a TV soap opera script - Hope was seen cruising Perth's Swan River with her mother. John and Bianca say they want to push ahead with the civil proceedings. It appears the pair have little interest in mediation and are keen to have the family's dirty laundry aired in court.