[itsme]

With "Let MobileSheets manage my files" unchecked MobileSheets leaves files where they are if they are already inside the MobileSheets storage location or a subfolder of it. Files are copied into the root folder of the MobileSheets storage location if they are imported 'from outside' to make sure that MobileSheets can be used offline. The MobileSheets storage location has to be 'local' - in internal memory or on a local SD card.
A solution for you would be to synchronize your folder structure on the NAS to an identical folder structure on the SD card with a synchronisation tool like FolderSyncPro https://play.google.com/store/apps/detai...rsync.full and import from the SD card with "Import local file".
FolderSyncPro works fine for me. There are other similar synchronization tools that should also work.

@Mike: is a combination of MobileSheets' "Sync Library" and "Let MobileSheets manage my files"=OFF intended to work? For fziegler the folder to sync with would be on his NAS. I would like to synchronize to a folder on my GoogleDrive - preferably using two way sync so that editing of ChordPro files is possible both in GoogleDrive and directly in MobileSheets.