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I was under the impression that you could not upgrade someone else in a Star-Alliance upgrade, but I'll leave that to those with better knowledge than I.

What I do know, is the fare classes required for Star Alliance upgrades are usually fully flexible fares, which are very expensive. In other words, if you do not require the flexibility of a full fare ticket, you can probably purchase a discounted business class ticket for the same, or even less money and not have to worry about not being able to upgrade.