the ruling (ruling over you) might be MAINLY for the company's books, but a % apportionment will be advised for the shareholder's books
i suggest there is a formula how can there be a different formula for each demerger? can't be the formula is on the ato website capitals gains and demerger
remember, taxation is theft by a mafia group that should be working for you to manage community infrastructure only
problems arise when infrastructure AND immoral people need to, beg to, be managed