[mgd]

I always leave the songs/pdfs as is. Create New Song, select PDF and Audio, fill in the fields, and that's it.
Never use the import function.

I manage all my scores outside of MS and have the MS data folder pointed to a parent directory. After having imported a (new) score once all subsequent changes I do outside of MS are visible in MS without any further intervention on my part.

All annotations drawn into the scores are left in place. Therefor when the page layout changes which happens from time to time when I'm working on the lilypond sources of a score, I have to erase the old ones and redo them which seems to be the only intervention occasionally required.

Regards,
Michael