-- Laura Ruffino met her best friend, Liz Diamond, in the fifth grade.
As adults, they both had children -- two girls for Ruffino and four girls for Diamond -- and kept their tight bond, Ruffino told ABC News.
But in August 2014, Diamond, a single mom from Orchard Park, New York, was diagnosed with brain cancer, Ruffino said. She died just months later.
"When we got in the car, she asked me, if anything ever happened, if I'd take her daughters. And I said, 'Of course,'" Ruffino said. "It wasn't even a thought."
Ruffino is now seeking custody of Diamond's daughters, who are living with her. But Diamond's ex-husband, Elyson Pagayonan, appeared in court to contest the Ruffinos' permanent custody of his children according to Leonard Berkowitz, a lawyer for the Ruffinos.
Pagayonan has not filed papers for custody of his children, according to the lawyer.
Laura Ruffino said that one morning in December, Diamond wasn't feeling well and called Ruffino to take her to the cancer center.
"It's like your whole world comes to a halt," said Ruffino, from Buffalo, New York. "That day, her MRI was not good," Ruffino said.
When Diamond asked her to take care of her children, according to Ruffino, she obliged.
"I would always want someone to do that for me. Her kids and I were so close anyway, because she was my best friend. I wanted to give her peace," Ruffino said. "I can't even imagine what she had to be going through."
Ruffino said it was a slow transition for Diamond's girls -- ages 5, 7, 8 and 12 -- to move in with the Ruffinos.
"As Liz got sicker, she and the girls would stay with us for periods of time," Ruffino said.
In April 2015, Diamond passed away.
Ruffino said she'd describe her best friend as "love."
"She was non-judgmental. Liz was my person," she said. "That person that you could be anyone in front of, would never judge you. Which I think is so rare in life to find."
Ruffino's husband, Rico, said "The girls are doing awesome." "They're all going through a difficult situation" but "they're doing really, really well, considering."
"They're great kids," he said, adding that, "They're my kids now."
And Laura Ruffino said the girls, including her 12- and 13-year-old daughters, are "all best friends" and "already sisters."
"They fight, they share clothes, all those things," Laura Ruffino said.
Efforts to reach Pagayonan were unsuccessful and messages left with his lawyer were not returned.
"They’re living with the family they know," Berkowitz told ABC News of the children. "It would be inhuman for them to be ripped from the only parents they now know."
Pagayonan and Diamond divorced about four years ago, according to Berkowitz.
Patricia Kaminski, Diamond's aunt from the San Francisco area, said her family fully supports the adoption. Her brother did not immediately respond to a request for comment.
“I think it’s remarkably generous for Laura and her husband to do that," Kaminski said. "I know Elizabeth’s family is very happy with that family. The rest of the family believe it’s an excellent outcome for the children.”
Rebecca Joy Lesniak, who worked with Diamond at the Buffalo Wellness Center, told ABC News that Diamond had spoken fondly of the Ruffinos and believed they could provide her children a "stable family."
"She was friends with Laura for many years and I heard only positive things," Lesniak said.
Laura Ruffino said she'd asked her best friend what she would consider her symbol, and Diamond told her "light." Now, in "random times," she said, like a bright sunshine or a bonfire, "I feel her and I know she's here."
The Ruffino family has set up a You Caring fundraising page to help cover the added living and college expenses and over $45,000 has been raised so far, according to the website.
Because of an editing error, and earlier version of this article mistakenly described in one passage the relationship between Pagayonan and Ruffino. In fact it was Diamond, the children's late mother, who was married to their Pagayonan and who divorced him about four years ago. We regret the error.