G'Day,
I expect someone will correct me if I'm wrong, but I think it goes something like this;
It is illegal to operate a company under another operator's AOC, however I think you can operate as part of the company holding the AOC, by crosshiring your machine to them and having them employ you as a pilot. You can have your own trading name but it must be added to the AOC and all your invoices to clients must have the AOC holding company's ACN printed on them