If you don't have status with United, little chance of getting Economy Plus. And not everyone needs to go thru Sydney to get to their destination. He did not say where his child was going to school. If in Queensland, I'd prefer to change planes in Auckland rather than Sydney. Likewise, same options for other cities in OZ. I mentioned Air New Zealand because it provides another viable and more than acceptable option for getting to Australia on United miles. And if no seats are available on a non-stop United to Sydney, changing in Auckland is fine. Not sure what you are getting at about "most direct route," as have used United miles many times to go Air New Zealnad through Auckland.