@just get on with it said:
Could Kanga or anyone else out there advise how this is dealt with in Qld legislation?
In QLD you can vote by returing your Agenda suitably completed with how you wish to vote each item. So the agenda is in effect a voting paper.
If any motion is significently (not sure how we actually define this) changed the postal vote if it was voted for the motion (origional), now is declared against the changed motion.