Hi,
we can add support for the "Movie Collection" tag from the nfo, please send an example nfo file to support [at] conceiva [dot] com so we can test to make sure it works correctly. This will also help us to fix the Catalog number issue.

For Movies the Series field is populated with the Movie Collection value if you get this value from an online metadata lookup so it is already possible to use this in an active playlist for movies to group them by collection.