Gina Rinehart.

Gina Rinehart: her daughter was offered $25m to walk away from court action. Photo: Bloomberg

Mining magnate Gina Rinehart has been ordered to hand over any agreements between herself and her two youngest daughters which prohibit her children from voicing support for a trustee who their mother has not approved.

The NSW Supreme Court on Tuesday heard Bianca Rinehart had been offered a $25 million loan to walk away from the court action, an offer which she rejected.

The proposal was made through Mrs Rinehart's bodyguard, Kevin Withers, about a year ago.

It was only weeks later that Hope, now 28, struck a deal with her mother and withdrew as a plaintiff in the family battle.

Barrister Chris Withers, for John Hancock and Bianca Rinehart, told the court he believed there may be a similar agreement with Hope which may prevent her from voicing her opinion in the case over who she would like to see replace her mother as trustee of the $5 billion family trust.

John and Bianca sued their mother days before the family trust was due to vest, accusing her of breaching her duty as trustee and failing to act in their best interest.

Youngest daughter Ginia sided with her mother.

The trust was set up by the children's grandfather Lang Hancock and holds 23.4 per cent of the flagship family company Hancock Prospecting.

Days before the case was due to be heard in October, Mrs Rinehart unexpectedly relinquished her role as trustee and the conflict is now centred on who will replace her.

Bianca Rinehart has been nominated but is not supported by her sister Ginia. Hope's lawyers have expressed support for Ginia's alternative suggestion and Mr Withers told the court on Tuesday it would be important to know whether Hope's position had any constraints.

Judge Paul Brereton said any loan agreement would be relevant when taking into account any reliance on the wishes of the children.

“Their wishes are a real consideration and the weight to be given to them is an issue in the proceedings.”

Therefore, he said whether their wishes were expressed “freely or whether their wishes were expressed with some form of compulsion or restraint is a fact in issue in the proceedings”.

The hearing continues on Tuesday afternoon.