Flying MEL-KUL-PVG (stop - Disneyworld, 2 days), then Ticketed PVG-HKG-SYD-MEL - 72 hour valid

We have 3 sets of tickets; not sure which Visa makes the best sense. We live in Australia - and are planning a 2 day trip to Disneyworld in PVG.

If we flew the above - MEL-KUL-PVG (stop - Disney for 2 days) - then return PVG-HKG-SYD-MEL - (on a separate ticket) - would this be valid for a 72 hour Visa? Or would we need something different? This would be for 2 Americans, and 1 Aussie travelling together.