They had hoped to raise $1,500 for the Refugee Immigrant Center for Education and Legal Services, or RAICES, a Texas-based immigrant legal services provider.
A little over a week later, they exceeded that goal thousands of times over: As of the morning of June 25, their campaign had raised a staggering $20.2 million, and garnered donations from 526,000 Facebook users, according to the campaign site.
At one point, for about two hours on June 20, the viral campaign was raising about $10,000 a minute, according to the San Francisco Chronicle.
The money raised will be used by RAICES to fund bonds to allow parents to reclaim detained children and offer legal representation for families and unaccompanied children in immigration courts in Texas.
The photo that triggered the Willners' response shows a 2-year-old Honduran asylum seeker crying as her mother is searched and detained near the U.S.-Mexico border on June 12 in McAllen, Texas, according to the Chronicle. It was taken by John Moore of Getty Images.
It has generated some controversy because the child was not separated from her mother for more than a few minutes while they were searched, according to the Washington Post, but has been used to represent the distress that other children who have been separated from their families at the U.S. border are going through, according to witnesses cited in media accounts.
"The photo is heart-wrenching and represents the fear kids face at the border," wrote Malorie Lucich, acting spokesperson for the Willners, in an email to The Almanac. "We're focused on providing RAICES with the resources needed to reunite those kids with their parents as soon as possible."
In recent weeks, more than 2,000 children have been taken away from their parents as part of a Trump administration policy, which seeks to criminally prosecute all immigrants who illegally cross the border, according to the New York Times.
The administration launched a "zero tolerance" immigration policy in April, which laid out plans to prosecute adults who attempt to enter the country illegally and separate them from any children they might bring with them.
Children from Central America separated from their families by immigration authorities at the border have been documented crying and in great distress, including in a seven-minute recording released by ProPublica.
More than 100 children in detention are under 4 years of age, and the children are initially held in warehouses, tents or box stores that have been converted into border patrol detention facilities, the publication reports.
On June 20, President Trump signed an order purportedly ending the policy of separating families at the border, but continuing the "zero tolerance" policy.
Charlotte Willner wrote on the fundraising page: "Make no mistake that the administration is changing course because people spoke out. You spoke out. You showed that you're not okay with this, that none of this okay, and that you won't stand for it. This fundraiser started with the hope of reuniting maybe one family, but it grew. It grew so big that it couldn't be ignored. It grew to a community, to a place that will help all families separated. And it's groups like this and people like you that are responsible for progress in a matter of days, so that mothers and fathers can hug their children again. Your voice and actions matter. Keep them going strong."
RAICES released a June 18 statement, also on Facebook, expressing gratitude for funds generated through the Willners' campaign. "Thanks is inadequate for the work these funds will make possible. We know it will change lives. We know it will save lives by keeping people from being deported to unsafe countries. We've been occasionally crying around the office all day when we check the fundraising totals. This is such a profound rejection of the cruel policies of this administration. Take heart. There are terrible things happening in the world. And there are many people who are deciding not to look away but to do something."
According to Lucich, RAICES has started a joint project to join forces with other organizations so all of the children separated from their families can be located, reunited with their family members and receive pro bono legal help.
She reports that the organization has added staff who will meet the buses that transport immigrants in order to better track "who's where and advocate for them," she told The Almanac in a written statement.
"We also heard that fathers are only allowed to call their kids in detention centers if there's $25 in their commissary, which of course they don't have. So RAICES covered this for fathers in detention," Lucich continued.
Go to is.gd/raices443 to access the Willner's fundraising campaign online.
In addition to running their campaign through Facebook, the Willners have closer Facebook connections. National Public Radio reported that the two previously worked at the company, though now Charlotte works at Pinterest and Dave at Airbnb.
Facebook executives Mark Zuckerberg and Sheryl Sandberg both donated undisclosed amounts to the campaign, Politico reported.
The Times cited Roya Winner, a Facebook spokeswoman, who said the Willners' page is the largest single fundraiser in the company's history.