Mr Hardcastle returned from war with post-traumatic stress and Mrs McGregor remembers him living with her and her mother in the late 1940s before he eventually ended up in Lake Alice in Rangitikei where he died in 1960.
Marton RSA's Barry Rankin, who tracked down the Mr Hardcastle's grave using old council records and maps, said earlier this year there were others buried in unmarked graves with little or no information about them.
Lake Alice was a maximum security psychiatric facility which closed in 1999.
There were accusations of mistreatment of patients in the facility and in 2006 the
New Zealand Herald
reported the Government had apologised to 183 former patients and paid them $10.7 million compensation.
Mrs McGregor said she was pleased her uncle now had a grave with a name and was grateful for the work Mr Rankin had done in tracking down her uncle and Veterans' Affairs for the funding.
"But there's others there and I just want to find the history."