Mushroom deaths: Don and Gail Patterson's family make a major move after their deaths following Beef Wellington lunch

The grieving family of two of the victims in the alleged death cap mushroom poisoning case have moved to settle their estates almost a year on from the tragedy.

The family of Don and Gail Patterson have officially applied to the Supreme Court for probate as their former daughter-in-law prepares to face trial.

The couple, both 70, and Gail's sister Heather Wilkinson, 66, all died within days of eating a Beef Wellington meal that allegedly contained poisoned mushrooms

The lunch was allegedly prepared by the Patterson's former daughter-in-law, Erin Patterson, at her home in Leongatha in Victoria's Gippsland region on July 29 last year.

Heather's husband, Baptist church pastor Ian Wilkinson, 68, survived the alleged attempted poisonings, while Ms Patterson's estranged husband pulled out of the lunch at the last minute.

Ms Patterson pleaded not guilty to murdering her in-laws and attempting to murder her estranged husband during a LaTrobe Valley Magistrates' Court hearing in May.

She faces three murder charges over their deaths and is also accused of five counts of attempted murder of her estranged husband Simon Patterson.

Almost a year on from the fatal lunch, the family of Mr and Mrs Patterson have moved to settle their estate by filing for probate, the Herald Sun reported.

Don and Gail Patterson (pictured) died after eating an allegedly poisoned meal at Erin Patterson's homeon July 29 last year

Don and Gail Patterson (pictured) died after eating an allegedly poisoned meal at Erin Patterson's homeon July 29 last year

The Supreme Court of Victoria website defines probate as: 'The process by which the Court approves that the will is valid and that the executor(s) can act on the will.'

The website states 'When a person dies leaving assets in Victoria, usually the executor of a person's will or the closest next of kin (where there is no will) has to finalise the deceased's affairs.'

The website adds this generally involves collecting or gathering all of the deceased assets, paying any debts, and distributing assets to entitled persons.

The executors listed on the two wills of the couple are Nathan Patterson and Anna Terrington. 

The wills are dated November 2, 2018 and are listed as 'under review'.  

The court reviewing a application is common practice, an estate lawyer told the Herald Sun.

In order to obtain a grant of probate, a probate application requires executors or administrators to file a number of documents with the Supreme Court. 

Erin Patterson (pictured) officially pleaded not guilty in May to murdering her in-laws and attempting to murder her estranged husband

 Erin Patterson (pictured) officially pleaded not guilty in May to murdering her in-laws and attempting to murder her estranged husband

These include the original will, a certified copy of the death certificate, a statement of the deceased's assets and liabilities and an affidavit. 

After these documents are filed, the court will usually either grant probate or request more information from the executors.

Once probate is granted, the executors can deal with the assets of the deceased.

The lawyer said the nature of the Patterson's deaths would have delayed the receipt of the death certificate.

He added determining the Patterson's assets could be another reason why probate was only applied for almost a year after their deaths. 

'Often, assets pass from one spouse to another after death automatically,' the lawyer told the Herald Sun.

'Accordingly, working out whose assets were who's at particular times may be the cause of the added delay.'

Erin Patterson remains behind bars and will reappear in court for an administrative hearing in August.