keepWithTag for a score

[David F.]

Let’s say I have a score:

myScore = \score { … }

After my score is built, I’d like to keep/remove tagged sections from the music 
inside my score.

How might I accomplish that?

I’ve already tried to decompose/recompose the score, like so:

\score {
        \keepWithTag #’myTag
                #(ly:score-music #{ myScore #})
}

But I’ve gotten some weird results (like the last system being ragged) and I 
don’t really want to throw away the original score because it has stuff like 
headers in it.

Any ideas would be greatly appreciated.

David