The various parties squabbling for a greater share of the Labor giant's fortune will gather behind closed doors next month in an attempt to nut-out a private settlement and avoid a public trial.

Mr Wran died in April last year aged 87 after suffering dementia. He was premier of NSW from 1976 to 1986. He left a fortune estimated to be worth about $40 million, largely comprising a property portfolio following a successful business career post-politics.

Mr Mason was the president of the NSW Court of Appeal from 1997 to 2008 and the NSW solicitor-general for a decade before that.

The parties have been ordered into private mediation on November 2 and are to report back on November 20. NSW Supreme Court Justice Philip Hallen has also ordered the fees for mediation be paid out of the estate.

Glenn Wran, the son of Wran's first wife Marcia, launched legal action against Kim Wran Sheftell, his half-sister and the estate's executor, earlier this year.

Neville Wran's youngest children, Harriet and Hugo Wran, by his second wife Jill Hickson Wran, have since joined the claim, as has his New Caledonia-born god-daughter Helene De Poortere. Mrs Hickson Wran is also a defendant.

During a hearing in the NSW Supreme Court in May, Justice Hallen was told the actual estate is valued between $700,000 and $1.6 million. But the notional estate, which could include superannuation, family trusts and real estate held with a joint tenant, is thought to be worth up to $40 million.

The court has previously heard Mrs Hickson Wran owns much of the property in the notional estate and under her late husband's final will is the beneficiary of certain personal effects, as well.

Harriet Wran is currently held on remand charged with the murder of drug dealer Daniel McNulty in Redfern in August last year. She will face a committal hearing alongside her co-accused and reported boyfriend Michael Lee in Central Local Court on Thursday.