your first option "keep the books on a NAS, but use a local Metadata" seems just right for what I'm looking for.
I've found this thread
https://www.mobileread.com/forums/showthread.php?t=84390
I wonder if it will work once I disconnect the drive.
well, I tried the catalog option and it could be a good option.
If add new books, for example, will the catalog be automatically updated to show the new entry or do I have to generate a new catalog?
thnx a lot for the quick answer, theducks