Plug-in suggestions regarding melody removal, accompaniment removal, part separation

Hello, dear friends.

I use MuseScore mainly for three things:

1. for writing out simple piano melodies,
2. for writing out accompaniment parts for the piano, and
3. for writing out three-part or four-part harmony for saxophone or clarinet, by transposing existing piano scores and separating the voices.

Without going into detail, I generally just import an existing piano part, and try to convert the existing notes for whatever need I happen to have, whether to separate them into harmonizing parts, whether to remove the accompaniment and retain the melody, or whether to retain the melody and remove the harmonizing notes.

I have often wished that there were a way to work faster while doing all of this, by means of a plug-in that would do it automatically.

First, I wish that there were a plug-in that would at least attempt to separate several voices automatically into separate "parts."

Second, I wish that there were a plug-in that would isolate the top notes of the entire score, and remove all the rest, leaving behind what is presumably the melody, or close to it. (My current work does not require great precision, so it would not be the end of the world to lose a few notes of the melody for the sake of saving time, as I could add them in manually)

Third, I wish that there were a plug-in that would work in reverse, that would isolate those top notes of the entire score, and remove them, leaving behind harmonizing voices alone, more or less.

Anyway, just some thoughts.