- Get a tutor for maths and physics so she has the best chance of getting good passes in her HSC exams. Most airlines require it and it is the best use of her time as a 15 year old.
- Join the Australian Air Force Cadets. Irrespective of whether she wants to pursue a military flying career in the future, the AAFC offers several advantages for young people like her. These include leadership opportunities, very cheap flying lessons, exposure to people who are in the industry, and would possibly improve her self discipline.
- Get her to research all of the cadet pilot opportunities available with major airlines. It's a fluid situation and will be different in a couple of years when she is ready to apply, but the more knowledge she has, the better she can prepare. If airline flying is her goal, cadet pilot programs are the way to go.
- Consider obtaining a CASA class 1 medical, or at least visiting a DAME to be certain she is eligible.
Good luck to her. Regardless of whether she ends up doing it, having a goal at that age gives her a massive advantage.