The Premiership six will attempt to rally fellow top-flight clubs amid their crusade for answers from under-fire chairman Murdoch MacLennan with a date set for a showdown meeting.
Rangers, along with Aberdeen, Livingston, Motherwell, St Mirren and St Johnstone, wrote to the league's governing body expressing "serious concerns" over the recent independent governance report.
They were dismayed that the SPFL executive had received a first draft of the report and made changes before the SPFL board had had a chance to meet.
They also felt it was inappropriate that Maclennan had spoken publicly before the SPFL board had met to discuss the report. In response, the Hampden beaks hit back, claiming the letter included a number of "factual inaccuracies." Now the six have invited fellow members clubs to attend a meeting before the end of this month to further address the issues set out in the stinging letter.