I've had mixed results doing this. Granted none of them involved OZ, but across Star Alliance theoretically the ability should be the same. I once flew UA DAY-ORD-IAH, and on a separate ticket flew SQ IAH-SIN-BKK. Check-in agents in Dayton were unable to through-check and I had to collect my bags and re check them in Houston. I also flew TG KTM-BKK and SQ BKK-SIN-LAX on a separate ticket. This time the TG agents in Kathmandu were able to check my bags through to Los Angeles no problem. Both of the tickets on that trip were paid and not a mix of paid and award, but they did involve different classes of travel. I should also note that this was nearly 7 years ago. I think in the computer systems it should be doable but it may just come down to whether the check-in agent knows how to do that or not. Your itinerary only involves two flights and I get the impression that foreign check-in staff are generally better trained than American ones so I personally would be reasonably optimistic about it.