The ruling body of the NSW Liberals declined to suspend, investigate or change the rules after an operative linked to its dominant faction allegedly paid cash to prospective members to cover fees and stack a branch, leaked documents show.

Branch stacking allegations were raised early this year when two members of the NSW Liberal Party submitted separate statutory declarations claiming they had been pressured to join the party at an ostensibly casual lunch by former schoolmate Christian McLaughlan, a local branch president and Liberal moderate in Terrigal.

"He said he needed numbers," Annie-Louise Robson swore in a document obtained by the Herald and submitted to party headquarters. "We were reluctant."

Ms Robson, who like her partner Samuel Mallett, agreed, after he "said we would not have to be any more involved in the party".