The 12ft (3.6m) by 12ft grave was unmarked, and only discovered when councillors Maggie Hurley and Jade Hughes tried to help the woman searching for the graves of her brothers, who were twins born in 1962.
One woman, who gave her name as Joanne, told the she had found the grave of her uncle Joseph Morris, who was born in 1960.
“My family have been upset for years, not knowing where he is,” she said.
“They’ve finally got some answers now.”
One of those who has visited the mass grave is Gillian, whose sister was stillborn 48 years ago.
“Even though she was born after me, and she was a stillborn baby, we have always talked about her,” said Gillian.
Gillian said that knowing now that her sister could be buried there made “a massive difference” to her family.
Councillor Ms Hurley said she and Ms Hughes looked through records of burials and when they looked at one grave at the cemetery in Royton they “realised this was a mass grave”.
She said the discovery had “devastated this town”.
