The names of 648 co-workers who died in the 9/11 attacks were arranged on the Cantor Fitzgerald section at the Ground Zero memorial according to who knew whom best, it was revealed.

For the last 12 years, passersby may have assumed that the names on the Cantor Fitzgerald section of the bronze panels that wrap halfway around the north pool of the 9/11 Memorial were sorted randomly, rather than by age or initial.

But it has now been revealed that they were in fact arranged based on “meaningful adjacencies”, allowing the names of best friends and co-working relatives to sit side by side.

“They weren’t people who just worked together and went home. They made up the fabric of their lives,” Danielle Gardner – whose brother Douglas did not survive the attacks – told the New York Post.

Investment bank Cantor Fitzgerald lost almost three quarters of its workforce when American Airlines Flight 11 slammed into the north tower a few stories below is offices on floors 101 and 105.

More than any other financial firm, the bank was seen as a family-run operation that fostered close friendships and saw brothers, aunts, uncles and even parents working shoulder to shoulder.

The change was made after a campaign by survivors and relatives that fought for “meaningful adjacencies” rather than those organized according to age or initial.

Each name was inputted into a specifically-designed computer programme that grouped colleagues together according to who knew who best.

Co-workers, close relatives, best friends and even a beloved baby sitter are clustered on the memorial, according to the New York Post.

Danielle Gardner has also completed Out of the Clear Blue Sky, a documentary about the unprecedented losses suffered by the company.

Douglas Gardner, 39, worked on the firm for several years with childhood friend Douglas Gurian. An executive director by the time he left, Douglas Gardner and Douglas Gurian, 38, had known each other since before the first grade. They spent summers together on Fire Island, married about the same time – Gurian proposed at Gardner’s summer home – and even had children at about the same time, said the Post.

Tragically, Douglas Gardner was attending a meeting at Windows on the World, a restaurant on the top floor of the North Tower, when the building was struck. He and Douglas Gurian, a broker, did not make it out alive. Their names are close, with only trader Calvin Gooding between them, according to the Post.

Calvin Gooding, 38, met Douglas Gardner in college. The night before all three men met their tragic fate, Danielle Gardner called Calvin Gooding to ask if he would sing and speak at her brother’s 40th birthday party, set to happen on October 5, 2001, she told the Post.

“I’ll definitely want to perform and give a speech,” she said.

Mark Colaio, 34, and a senior managing director, talked bond broker brother Stephen, 32, into joining the tightly-knit firm. The elder brother often had a group of 25 employees over for parties at his Manhattan apartment and out to his Montauk beach house, his sister Jean told the Post.

“They spent a lot of time outside work and shared a lot of special times,” said Jean Colaio, adding that “they really looked out for each other – while working, as friends, and, I’m sure, on that day”.

Joining the Colaio brothers nearby is Thomas Pedicini, 30. As Mark Colaio’s brother-in-law, he was recruited into the firm’s equity department, the Post noted.

Stephen Hoffman, 36, and Robert Jordan, 34, went to college together and ended up at the firm as bond traders, Hoffman’s brother Greg told the Post.

They surfed and played golf together – they both even married school teachers, Greg Hoffman noted. With so much in common, the two families were very close, even joining Stephen Hoffman’s family for trips to the Jersey Shore.

“That’s the way those guys lived,” Greg Hoffman said, adding that “in the end, that’s the way they died, together”.

Daniel Shea, 37, and his brother Joseph Shea, 47, were both managing directors by the time they found themselves with a familiar intern – former babysitter Amy O’Doherty. Having known her since she was 13, it was only natural to offer her a tryout after watching how easily she multi-tasked juggling the kids and all their various activities.

“She handled it so effortlessly, and the kids were crazy about her,” Nancy Shea, Joseph’s widow, told the Post.

“She was indispensable to our family.”

Hired shortly after graduation in 2000, Amy O’Doherty was with the firm just over a year when the terror attacks occurred, Nancy Shea noted.

Rosanne Lang, 50, and an equities trader with the firm, was searched for by nephew Brendan Lang, 30, after the first plane hit, according to a relative who spoke to the Post.

Brendan Lang called his parents telling them he was going to find his aunt, he had a plan he said. He was a project manager working in the South Tower – across from his aunt’s North Tower office. Neither made it out alive, but Cantor placed their names next to each other despite Brendan Lang having never worked for the firm.

Bill “Scoop” Esposito, 52, and a partner at the firm, had survived the first World Trade Center bombing in 1993. He and bond broker Peter Milano, 43, led a pregnant women to safety during that attack, a relative told the Post.

It took them more than two hours to make it to the ground floor via the stairwell, but they did it, and Bill Esposito once again came to the rescue.

“When they got to the bottom floor, glass was falling. He pushed Peter out of the way and saved his life,” Bill Esposito’s daughter Susan told the Post.

Bill Esposito also bought senior vice president Thomas Strada’s wife a baby gift the day before the attacks, she had given birth only days earlier, she noted.

“Everybody knew everybody, there were friends of friends of friends,” she told the Post.