Yep I was just giving you a heads up. Usually SQ CS asks if you are "authorized" to access another person's reservation/account. In that case you may be fine, but it really depends on the agent. If you have access to your relative's KF account, just enter that when you call customer service (they typically ask to enter your FF number and password), and in that case you would be verified/authorized in their system. After that you can just let them know that you wish to upgrade a nominee's booking using miles (and proceed with the miles purchase). Hope this helps.