Glad you got confirmation that you can do this upgrade! I wish I had been more diligent about collecting Airmiles for this - that's a huge savings.
I did it in Universal Studios. Go to guest services before you leave the park to upgrade the tickets. It is on the far left side of the exit on your way out. I believe IOA closes earlier than US in August, so I upgraded in US.Just bumping this....
I'm going to buy the two day park to park tickets through Airmiles and I plan to upgrade them to a seasonal pass this August.
So I need to upgrade in the parks?