[itsme]

@anuzzo: you should know and understand that the folder / subfolder / file structure in the file system and the MSP database structure with songs, collections and other metadata are independent.
Just set the MobileSheets Storage Location to the top level folder of your folder structure (or copy your folder structure into your MSP Storage Location folder) and set “Let MobileSheets Manage My Files” to OFF.
Then you can keep your existing folder structure to navigate through your files and use collections, metadata and filters as proposed by Zuberman to navigate through your library within MSP. "Year" is available as a metadata field, orchestras can be stored in collections and if you need further refinements use one of the user specific fields.