Rinehart olive branch on control of multi-billion-dollar family trust New twist: Gina Rinehart offers her son, John Hancock, a position as a co-trustee of the multi-billion-dollar family trust. Gina Rinehart's battle to maintain control of a multi-billion-dollar family trust has taken a new twist, with Australia's richest woman offering to make one of her estranged children a co-trustee. The NSW Supreme Court has been told that Mrs Rinehart has written an "open letter" to her son, John Hancock, and daughter Bianca Rinehart with a deal that says "the first defendant would be willing to appoint a co-trustee" to the family trust, the Hope Margaret Hancock Trust. Two of Mrs Rinehart's four children are applying to remove their mother as trustee of the family trust alleging she acted "deceitfully" and with "gross dishonesty" in her dealings as trustee of the family trust. Proposed alternative: John Hancock, son of Gina Rinehart and potential co-trustee of the family's multi-billion-dollar trust. Photo: Steve Pennells The trust was set up in 1988 by her father, Lang Hancock, with her children as the beneficiaries. The two children are wary of an offer made by their mother to bring a legal battle over the trust, which controls about 25 per cent of Hancock Prospecting, to an end. "If only it were that simple," John Hancock said, when asked if making him a co-trustee would end the family feud. It is understood Mr Hancock has not yet seen the letter from his mother at the time of publishing, as it was sent straight to the court. Justice Patricia Bergin described Mrs Rinehart's offer as a "very big step." Christopher Withers, representing Mr Hancock, told the court "it was a step" but they would need time to consider it. Mr Hancock has been put forward as a proposed alternative trustee, along with Adelaide businessman Bruce Carter. Issues that would need to be sorted out might include who would get the casting vote if there was a deadlock in any decisions. In a bitter legal fight that has divided Australia's richest family, Mrs Rinehart is supported by her youngest daughter, Ginia. Her other daughter, Hope, is understood to not have taken sides after withdrawing from the legal action earlier this year due to financial reasons. The civil trial is set down for October 1.