That’s spot-on!
Whist brendjca can certainly rent the second property without a carspace and use that for the additional car, permanently / officially allocating that carspace to the unit that they occupy would require the consent of their Owners Corporation, and necessitate a Strata Sub-Division involving a re-survey of the Scheme, the production of a revised Strata Title Plan, and a valuation to determine the revised units of entitlement and levies for both Units.
All that information has to then be submitted to NSW Land & Property (inc the former Land Titles Office) so that the official records can be updated; for a further fee.
not worth the effort and the expense in my opinion.