5.1 and 5.5 are separate installs, they both have their own folder, and you can fire up any of the two whenever you want. So, you can import the AAF in any of the two versions that work. ( remember that it depeqnds from which Mediacomposer the AAF’s come from) The AAF folder is located in the Components folder of each Nuendo version, Hich you can find in the Steinberg folder in Program Files. So -if you really want to have the 5.1AAF filer intso 5.5, just swap the AAF folder. I am pretty sure it works. But the most simple way is just to fire up the Nuendo version you need.
Fredo