[sciurius]

I think it is slightly more complicated.
An instance of MSPro consists of a collection of settings, a database, and a collection of songs. Basically, all that gets included when making a backup (.msb). The database and songs can already reside in a user-specified location.
Theoretically (and maybe also practically) I could make a .msb for each musical project and load the appropriate .msb when switching projects. For this to work reliably, MSPro should keep track whether there are data changes that have not been stored in a backup and issue a big warning if so. Better still, automatically save everything in a .msb if necessary and restore the new .msb.
Maybe in combination with a backup option to not include the songs unless MSPro is configures to manage them.
Just thinking aloud...