[Zubersoft]

Yes, you can certainly import files directly from an SD card in MobileSheets on the tablet. Just tap Import->Local Files, tap the SD card icon in the file browser, tap the removable storage option, and then you can navigate to the folder containing your files on the SD card and import them. If Settings->Storage->Let MobileSheets Manage my Files is enabled, then MobileSheets will copy files from the import location to the storage location. You can uncheck "Let MobileSheets Manage my Files" if you don't want that behavior, but then you will be responsible for managing all the files and folders and this could have a negative impact if using certain features like the library sync feature. 

Mike