[Zubersoft]

If you want MobileSheetsPro to respect the paths in the backup file, you need to make sure on the "Restore Library" dialog that you change the "Restore To" dropdown to "Original File Locations". By default, all of the files in the backup will be copied into folders managed by MobileSheetsPro in the storage location. 

I'll run some more tests with smart buttons. When you say the "position of the mp3 are still lost at the synchronized device" does that mean the same device you restored the backup file on? Or a different device that you synchronized using either the library sync feature or a backup file?

Thanks,
Mike