Hi Kevin. It sounds like you might be able to do want you want with rehearsal marks. They're built into Lilypond and do pretty much what you seem to be describing. Details at http://lilypond.org/doc/v2.24/Documentation/notation/bars#index-rehearsal-mark A modification of your MWE using them:
\version "2.24.2" \language "english" melody = \relative c' { \set Score.rehearsalMarkFormatter = #format-mark-box-letters \time 6/8 \key d \major \clef treble \mark \default d8[ e8 e8] g8[ a8 b8] | \break \mark \default d8[ e8 e8] g8[ a8 b8] | \fine } \score { \new Voice = "mel" { \melody } \layout { \autoBeamOff indent = 0\mm } } The \set Score.rehearsalMarkFormatter = #format-mark-box-letters part reformats the marks to display as letters inside a box - the default is just a letter. By doing \default after the \mark Lilypond simply uses the letters sequentially. If needed, the position of the marks can be adjusted. Again, details on that are in the page linked above. -- Michael