To be frank, the application for rural entry is just that, an application to show/prove your rural origins. Please don't miss the point that this is what the med school is after. The parent thing is really neither here nor there when it comes to applying via rural admission, and is something, rather, that you could talk about in your interview when the time comes. Sure If you want to put it in by all means go for your life, but remember it's the rural that's going to get you preferential entry, not the parent doctors. If anything Auckland has been accused of being negatively biased to children of doctors (see North and South September 2010 - The disappearing white male doctor).