Similarly, if the original clearance included a restriction, e.g. ‘cross XYZ FL180 or below' then the issue of a revised clearance automatically cancels the earlier restriction, unless it is reiterated with the revised clearance.
You talk about the 4 elements of a clearance, and if you change the specific element that relates to the restriction then that restriciton is cancelled. That isn't what your own advice to pilots says. It says that if you reclear an aircraft restrictions relating to the previous clearance are cancelled.
Above and beyond that, please tell me the logic of a rule where you have a restriction due to crossing aircraft at FL210, so you give a requirement to be FL220 by a time/place. The aircraft is climbed to FL270, then FL290, and then FL310 as the upper levels become available, all while the aircraft is still in the FL's below the crossing problem. Why does it make sense that while you are not changing a level that has anything to do with the segment of the flight trajectory that the restriction relates to, that restriction keeps getting cancelled and having to be restated? It keeps getting said that this works and so the rest of the world can and should do it this way. Do you think you could open your mind to a different way of operating and even just consider that there are others out there that may have a better way of doing things. I am certainly not saying that Australia or Australian controllers have the answer to everything and do everything as efficiently as they could, but just maybe on this one, they have something.