oldmate & Kelpie, here's a bone to chew on...
Does the Qantas Sale Act apply to Jetstar and other Qantas companies? ..... the full complement of Australian and international air service agreements. ...
(Senate )Report - Qantas Sale (Keep Jetstar Australian) Amendment Bill 2007 [PDF]
(I haven't had time to look at it yet myself, could provide some questions & answers)
Some International Air Service Agreements apply to both Qantas
AND Jetstar IIRC, another avenue to investigate.