Barron Trump’s appearance in a family Christmas photo proves that Melania and former President Donald Trump are in “lockstep with one another,” according to a well-placed source.

The rarely seen 17-year-old posed for a holiday snapshot with his father, three of his siblings and other members of his extended family while his mom, Melania, was missing because she is caring for her sick mother, Amalija.

But Barron’s appearance is “truly monumental,” according to Melania’s former senior aide, Stephanie Winston Wolkoff, who told The Post we can expect to see more of the teen.

Barron has deliberately been kept out of the spotlight by his “strategic” mother, but was front and center in the photo posted by Kimberly Guilfoyle, Donald Trump Jr.’s fiancée, from Mar-a-Lago.

Sources said Guilfoyle would never have posted the photo without permission.

Wolkoff said Barron’s presence is telling: “Melania’s decision to include Barron in this family activity, even if she couldn’t be there herself, might be a significant turning point, potentially fostering a new level of support between Melania and Donald.”

“Barron’s appearance is truly monumental and shows Donald and Melania are in lockstep with one another,” she said.

“I believe we will be seeing more of him now. Nothing happens by chance with Melania.”

The last time Barron was seen with the wider Trump family was at the funeral for Ivana Trump, his father’s first wife, at St. Vincent Ferrer Catholic Church on Manhattan’s Upper East Side, in July 2022.

He was seen with both his parents in November 2022 at Mar-a-Lago when his father formally announced he was running for re-election and was also seen leaving Trump Tower with his mother in June of this year.

Wolkoff was once one of Melania Trump’s closest friends, and went with her to the East Wing of the White House.

But the two fell out bitterly, and Wolkoff went on to reveal tapes of their conversations, which included the then-first lady saying: “Who gives a f–k about the Christmas stuff.”

The Vogue alum also wrote a tell-all about her time with Melania in the White House, called “Melania and Me,” in 2020, in which she revealed how close the former first lady is to her parents, Viktor and Amalija Knav.

She told The Post: “Melania has always taken care of her parents. I pray for Amalija.”

But she added that conversely, the former first lady also “get[s] a kick out of keeping everyone guessing.”

As Page Six reported, insiders say Melania is set to “step up top-tier diplomatic appearances in 2024” after Trump scored a recent Supreme Court victory in his federal election subversion case.

The Trumpworld source said that following Melania’s appearance alongside fellow former first ladies at Rosalynn Carter’s funeral, she is “feeling more sure of herself — as both her husband’s representative and her own position as a diplomatic figure after her positive reception at the Carter funeral.”

“Melania realizes it’s her time to join the ranks of historic first ladies and leave her mark on history … She feels better prepared for her potential role the second time around,” the source added.

The source added that Melania also feels she can devote more time to the role since Barron is now 17.

She also appeared at a naturalization ceremony for new citizens at the National Archives.

Wolkoff has never shied away from giving her thoughts on Melania and earlier this month she said Melania will support her husband as he prepares for the 2024 presidential election.

She told CNN: “I do feel strongly that Melania Trump isn’t going anywhere. I believe that Melania will stay by Donald’s side. Throughout all of this, she is his partner in crime.”