Originally Posted by DreamHigh

You can just keep your OZ number on the booking! I used the Aeroplan SAUA tool and input the flight details, eticket number, passenger name etc., it'll search up your booking in the *A database and look for redemption availability. If it is available, it'll tell you the number of miles required. Once you confirm it through, the upgrade will push thru to your EVA booking immediately, so you can choose your seats and meals on the BR MMB. Aeroplan will send a confirmation receipt to your email. Your OZ number will remain intact.

BTW, you can use anyone's aeroplan account to process the upgrade. The name does not have to match. I used my brother's miles to upgrade.

For SQ miles, the process might be a bit different, I believe you may have to call Krisflyer. Since you are redeeming for yourself, it should be fine. Note that SAUA upgrades by segment! The Krisflyer agent probably won't be able to see the FFP on an EVA ticket.