The families of three children who went missing from the Bowraville Mission over 20-years ago are continuing their battle to solve the case.

16 year old Clinton Speedy-Duroux, 16 year old Colleen Walker and 4 year old Evelyn Greenup all went missing in the early 1990s.

The bodies of Clinton and Evelyn were found in bushland near the Bowraville Aboriginal Mission.

Colleen Walker has never been found but her clothes were discovered, weighted down with a rock in the Nambucca river.

A man has been charged and acquitted of the murders of Evelyn and Clinto, but the families say there is now new evidence.

Clinton’s aunt Leonie Duroux said they will march on Parliament House in Sydney next month seeking an inquiry, or a retrial.

“The Government has told us that they aren’t going to support a royal commission, and a parliamentary inquiry is not going to be supported,” she said.

“We’ve actually been told to walk away, move on, get some grief counselling, get more grief counselling.

“We pretty much just want to let them know we’re not going to walk away until we get some justice, because we believe the murders are solvable.”

Ms Duroux said the call in Sydney next month, will also be for changes to double jeopardy laws.

“One thing we would like to see, and we know it’s a little bit ambitious, is have a reform of the laws and maybe take the word “fresh” out, where it says the evidence must be “fresh and compelling”, she said.

“If we take the word fresh out, then possibly our evidence may get over the line.”