[BRX]

I modify my mobilesheets.db before copying it from my Android tablet to my Win10 laptop. To do that I bundled a number of calls of Sciurius' MSPReloc within a batch file.
The batch is attached, you need to adapt the paths of your installation of Perl and MSPReloc and the song file paths that you want to replace.
Note: I use this with MSP 2.1.9 that doesn't have relative paths yet.
If you have questions feel free to contact me directly.

 Thanks itsme. I hadn't set up Perl on my new W10 desktop again and was looking and hoping to avoid that. But I should do that anyway also for the other useful scripts of Sciurius. 

But I probably still need to know which parts I have to replace (including or without slashes) so I get correct relative paths. 

I think you will enjoy the new version because it converts the absolute paths to the new relative ones automatically (my remaining paths are a special case) so you won't have to edit your databases any more and they are interchangeable.