We stepped in after Liz Crowter was alerted to online pages that mocked her 16-year-old daughter Heidi.
Images of the teenager were taken from a Down's support group site posted by her mum and then shared amongst fellow trollers who made 'jokes' about the girl's looks.
Some of the things they wrote about Heidi are too offensive to be repeated here, but several were of a sexual nature.
The mildest was: "I'd do her," according to Liz, from Coventry.
The mum-of-four said she was 'horrified' when she discovered the photos were in circulation and were being used to attack her child.
She told Parentdish.co.uk: "I felt so angry and upset. It was very distressing."
And she said that Heidi – who is internet-savvy – had also seen the abuse and was "very hurt" by the things that had been written about her. Heidi's two older brothers, Dan and Tim, and younger sister Suzy, were also distressed by what trollers were saying about their sister.
"But they know how the internet works and just feel sad that there was nothing they could do about it," said Liz.
On the group's site, Liz had shared her experiences of being the mother of a child with Down's Syndrome and also went on trips and holidays with the group's members.
In October, she found her daughter's picture on a Facebook page which insulted people with Down's Syndrome and other learning difficulties.
She contacted Facebook and also West Midlands Police, who she said informed her it was not a matter for officers.
Over the weekend Mrs Crowter was told by friends that Heidi's picture had been put on a new page which insulted people with Down's Syndrome.
Liz said: "I felt violated and violated on Heidi's behalf. I'm disgusted that people can be so sick.
"It's not just Heidi, it's photos of other people's children as well."
The photos were originally hijacked to form the background of a "Meme", which was then posted on forums for other users to write a new "joke" over the top.
A Facebook spokesman told Parentdish.co.uk: "These images can and will be removed by Facebook; Liz Crowter would need to use this link to report unauthorised photos.
"Once the images are reported, they will be reviewed by our User Operations team – who are responsible for reviewing incoming reports and taking the necessary action.
"Across much of the wider web there are few controls on behaviour and the content that individuals can post. That isn't the case on Facebook. Facebook has a real identity policy, which makes people accountable for their actions and behaviour.
"When people on Facebook do find themselves in a situation where they feel uncomfortable, we encourage them to use our reporting tools so the content or activity can be investigated.
"We also have a set of rules that set out how people are expected to behave – the Statement of Rights and Responsibilities. These rules are intended to create a balance between enabling free speech and preventing harassment and abuse."
Liz said of Heidi: "She is a very independent young lady who is studying for her GCSEs at a mainstream school and doing a hairdressing course.
"She's funny, stubborn and very kind. "We're all very upset about what has happened."