[itsme]

In case I need a ChordPro song in 2 keys I just make a copy in MSP. This creates a second song (= database entry) in MSP that refers to THE SAME ChordPro file with independent meta data. I transpose the songs as required and set the "Keys" field in the song editor accordingly. Then I can add the songs to collections and setlists as usual.
Edits in the ChordPro file (fixing typos, adding/removing chords, changing line breaks etc.) show up in all versions, edits of meta data in MSP song editor have to be done independently per song.