Before you can do anything you need to find out what the current status of the complex title is and for this you need to go to the State dep responsible and obtain a current copy of the strata plans (In QLD they are called the CMS Community Management Statement) which show visitor parking, common areas and private areas. If this was done correctly in the 70’s I feel you are stuffed, but if they didn’t register the new titles that is a different ball game.