[BetterRed]

Then I must have misunderstood what you want to do, as I use that option almost every day to add dozens of 'book folders' in a single operation - each subfolder contains multiple files of the same 'text' in different formats.

If necessary move the individual book folders into an outer folder - 'books2add' - and use that folder.

If for some reason you cant move the folders into an outer folder, then copy the folders to an outer folder, or if you're short of disk space create folder links in the outer folder.

BR