The mother of missing Invercargill schoolboy Mike Zhao-Beckenridge has taken legal action to safeguard his possible stake in a Queenstown house.
Mike, 11, has been missing since March 13.
Estranged stepfather John Beckenridge, 64, broke a court order to pick him up from school at lunchtime.
Eight days later, Mr Beckenridge's car was found at the bottom an 88m cliff near Curio Bay.
No remains were found but the leading theory is a murder-suicide.
Now, the boy's mother, Fiona Lu, has taken legal action after her solicitors received a letter stating he had been excluded as a beneficiary of the trust that owns Mr Beckenridge's million dollar Queenstown home.
Ms Lu's solicitors went to the High Court after correspondence from Ulf Roger Henricson.
Close friends Mr Henricson and Mr Beckenridge own the Lake Hayes property as trustees of the Ozprey Trust.
A High Court judgement of Associate Judge Robert Osborne, released yesterday, gives the background.
''Ms Lu is unaware of the terms of the trust deed but believes that her son may be a beneficiary,'' it reads.
''Mr Henricson has recently sent an email to Ms Lu's solicitors - his email asserts that Ms Lu's son has now been excluded as a beneficiary.''
The judgement says Ms Lu is making a claim in the Family Court against the trust, through the Property (Relationships) Act 1976.
She sought a court order appointing Public Trust as the trustee for the Ozprey Trust, in substitution of Mr Beckenridge, and an order that Mr Henricson does not have to be served papers in person.
Swedish airline pilot Mr Henricson has been quoted in media saying Mike Zhao-Beckenridge was desperate to return to Queenstown to live with his stepfather.
Mr Beckenridge and Ms Lu married in 2007 but separated in April 2013.
Since helicopter pilot Mr Beckenridge went missing, no one has been living at the property.
The judgement says it is understood the mortgage is in arrears. A case management conference has been set down for August 18.