A never-before-seen family photograph of missing four-year-old Gus Lamont has emerged after his grandparent scuffled with media outside court this week.

Josie Murray, 75, was fined $10,500 and banned from owning firearms for five years after pleading guilty to possessing a gun silencer that was discovered during the search for Gus at the family's remote South Australian cattle station.

As she left court, Josie - who transitioned to a woman several years ago - elbowed past one journalist, causing another to fall, and ignored questions about Gus. 

Murray's court case, unrelated to Gus's disappearance, came as a rare photo of Gus surfaced publicly for the first time, showing three generations of his fiercely private family together before Gus vanished.

Gus's father, Joshua Lamont, beams at the camera alongside his partner Jessica, who holds their young son firmly on her hip. 

Jessica's mother, Shannon Murray, stands next to her daughter in the photo, smiling broadly with a glass of champagne in front of her on the bar.

The family appear relaxed and happy, enjoying a drink together, while Gus, thought to be about two years old in the photograph, is distracted by two bottles of water.

The pic, published in a local newsletter, was taken at a community event at the Yunta Race Club and captioned: 'The Oak Park Crew, Joshua, Jessica, August and Shan.'

It has been more than eight months since the little boy disappeared, with police declaring the case a major crime investigation and confirming a member of his extended family is a suspect. 

But after dozens of interviews, multiple searches and months of inquiries, investigators have yet to reveal the answer to one key question: When was the last time Gus was seen alive by anyone who is not a suspect in the case?

Daily Mail first posed that question last November, when police said the little boy had 'wandered off'. Despite repeated requests, police have declined to answer.

Detectives have been told Gus was last seen playing in a sandpile outside the remote homestead owned by Josie and Shannon Murray on September 27 last year 

Gus was said to be at home with grandmother Shannon and baby brother Ronnie, while his mother and grandmother Josie tended sheep elsewhere on the property.

However, in February, police alleged key timelines on the day Gus vanished 'did not match up' and declared his disappearance a major crime investigation.

Detectives also revealed that one of Gus's grandparents had become a suspect and stopped cooperating with police - a claim both grandparents deny. 

Police have refused to elaborate, or confirm which grandmother is now their suspect, leaving the events of the day Gus vanished shrouded in mystery.

In the first weeks of the hunt for him, a friend of Joshua's told the Daily Mail the musician did not get along with Josie and was unhappy about his children living on the farm.

Daily Mail also revealed Joshua had been renovating a home about two hours away in Belalie North for his young family, with plans to move there before Gus started school.

While Josie does not appear in the newly uncovered family photograph, the image paints a picture of a time when the family appeared far more united.

For years, Joshua was a regular at Oak Park Station, helping around the property and even filming music videos for his band in the paddocks.

It is understood he and Jessica had separate accommodation on the station and lived there on and off after Gus was born.

Exactly when and why the family relationships soured has not been made public. 

In January, police executed search warrants at the remote property, seizing several items, including vehicles and electronic devices, for forensic examination.

After those fresh searches, police publicly ruled out both of Gus's parents as suspects, while revealing the unidentified grandparent was now a person of interest.

It is understood Jessica moved out of Oak Park Station around the same time, relocating to Adelaide with Joshua and their youngest son, Ronnie. 

On Friday Josie faced Adelaide Magistrates Court, for sentencing after pleading guilty to acquiring, owning or possessing a sound moderator, a device more commonly known as a silencer or suppressor.

She was charged in February - in the midst of the hunt for the missing youngster - and she entered her plea in writing ahead of Friday's sentencing hearing.

The device, which is designed to reduce the noise of gunshots, was found on the property on January 15 during the massive police search for the child.

Murray appeared in person for the hearing, supported by close friend Bill Harbison, who spoke to the media on behalf of the family when Gus first disappeared. 

The court was told Murray had owned the silencer legally for several years but did not inform authorities she had it when the law changed in 2017, requiring permission.

Murray's lawyer Andy Ey said it had been a 'very difficult time' for his client.

'To address the elephant in the room, this has been an extremely difficult time for her family - her grandson went missing last year,' he said. 

'This is a serious matter, but it is not some James Bond movie where a villain or assassin is walking around corners taking out targets with barely the whisper of a gun.'

Police have confirmed they will return to the property in the coming weeks.