THE Hanging Rock Action Group has not backed down on its plight to save the precinct from development, saying too much will be lost if the proposal goes ahead.
The Macedon Ranges Shire Council has approved a resort and conference centre to be built at the Rock.
It says there was only one suitable option to save the Rock, due to the "dire financial situation" of the centre.
A 5000-signature petition calling on greater community consultation, presented to council last year, failed to change council's position.
However action group member Hilary Roberts said a picnic, to be held at the Rock this month, could help sway council's decision.
He said the picnic, organised by the action group, would help spread accurate information about the development.
Picnic at Hanging Rock star Anne Lambert will speak at the picnic, alongside local MPs Amanda Millar and Joanne Duncan, who have thrown their support behind the group.
"We are hopeful council may reconsider community consultation at its next monthly meeting because of all this support," Mr Roberts said.
"At the moment though they're still digging their heels in."
The picnic will be held at the petanque pavilion, Hanging Rock Reserve, at Woodend, on February 23.