Originally Posted by SFOTRAVELER
...I just want to make sure I understand: I have a ton of Mileage Plus miles almost all from UA (with some AC). I can't use them to upgrade a purchased Air New Zealand coach ticket to business? I would love to take the new SFO-AKL nonstop...
I don't know about other airlines but, as far as I know, you can only upgrade flights on United or Lufthansa when using United's MileagePlus miles. You can certainly
earn more MileagePlus miles on all the Star Alliance members, but can't do upgrades on all of them. You can probably get better/more specific information about United in the MileagePlus forum.
Hope this helps a bit.