For my music A level, about 12 years ago, I wrote a sonata-style string
quartet that I'm trying to resurrect and output in LilyPond. It has a
section that repeats between the start of the first full bar (there's a
pick--up before that) and the end of bar 39. The repeated section starts in
D major and the key is changed to A major part way through. On the repeat,
the key has to be change back to D major so the start of the repeat is in
the right key. However, once the repeat has been played, and the music is
going on past the end of bar 39, I want the key to remain in A major. In my
notation software, I can do this by putting a first-time section just before
the repeat bar, and putting the key sig for D major in there. However,
LilyPond complains about this with "warning: Two simultaneous key-change
events, junking this one \key a\major", which I can understand, but want to
avoid. Can anyone proffer advice on how to notate this correctly?