They closed that loophole with the implementation of eUpgrades. As of now, you can only apply for eUpgrades at the upgrade window of the person whose credits are being used.

They have also implemented a policy that if your upgrade is confirmed, and you later unrequest it, you would have to find a fare bucket that still has space. This was due to people requesting upgrades, then arriving at the airport with no/incorrect cert. AC then had to create an opening in your original fare bucket (in effect penalizing them by creating extra space in low-cost buckets).

Basically the new policy eliminates Super Elites from sponsoring Elites on the same flight.