Originally Posted by CO Insider

That's right mnmag. If the Platinum or Gold Elite cardmember is traveling on a reward redeemed from their own account, they can request a companion upgrade for someone else traveling on a revenue ticket or a reward ticket redeemed from their account. In all other cases, the Platinum/Gold Elite companion benefit only applies to revenue tickets. Meaning, Elite cardmembers on reward tickets can't be added as someone else's Platinum or Gold companion.