We upgraded our son's DVC PAP when we were there a few weeks ago. We did it at MK Guest Services. It took forever, but it worked fine. He was upgraded to the Platinum Plus. DW and I still have active DVC PAP's and our son is linked to my wife's account. We have to use her account to edit and download the Photopass photos, but it works fine. We made sure that his band was scanned when we used Photopass. The photos do show up in my account, but when I try to download them, it shows a charge to do the download.
Saw you posted asking about using the DVA to pay for tickets and dining plan-you can't use the DVA at guest services to do the upgrade you mentioned-I was pretty certain of that fact but asked anyway to be sure when I upgraded from a reg DVC pass to DVC gold in Oct and It was confirmed-it wasn't a big deal for me (the price difference was $21) but just want to make sure you don't specifically put money into the DVA thinking you can use it for this purpose.