Editing Using marklines in a Frenched score

Using <code>MarkLine</code> contexts (such as in [https://lsr.di.unimi.it/LSR/Item?id=1010 LSR1010]) in a Frenched score can be problematic if all the staves between two <code>MarkLine</code>s are removed in one system. The <code>Keep_alive_together_engraver</code> can be used within each <code>StaffGroup</code> to keep the <code>MarkLine</code> alive only as long as the other staves in the group stay alive.

<lilypond version="2.24.0" full>
bars = {
  \tempo "Allegro" 4=120
  s1*2
  \repeat unfold 5 { \mark \default s1*2 }
  \bar "||"
  \tempo "Adagio" 4=40
  s1*2
  \repeat unfold 8 { \mark \default s1*2 }
  \bar "|."
}
winds = \repeat unfold 120 { c''4 }
trumpet = { \repeat unfold 8 g'2 R1*16 \repeat unfold 4 g'2 R1*8 }
trombone = { \repeat unfold 4 c'1 R1*8 d'1 R1*17 }
strings = \repeat unfold 240 { c''8 }

#(set-global-staff-size 16)
\paper {
  systems-per-page = 5
  ragged-last-bottom = ##f
}

\layout {
  indent = 15\mm
  short-indent = 5\mm
  \context {
    \name MarkLine
    \type Engraver_group
    \consists Output_property_engraver
    \consists Axis_group_engraver
    \consists Mark_engraver
    \consists Metronome_mark_engraver
    \consists Staff_collecting_engraver
    \override VerticalAxisGroup.remove-empty = ##t
    \override VerticalAxisGroup.remove-layer = #'any
    \override VerticalAxisGroup.staff-affinity = #DOWN
    \override VerticalAxisGroup.nonstaff-relatedstaff-spacing.padding = 1
    keepAliveInterfaces = #'()
  }
  \context {
    \Staff
    \override VerticalAxisGroup.remove-empty = ##t
    \override VerticalAxisGroup.remove-layer = ##f
  }
  \context {
    \StaffGroup
    \accepts MarkLine
    \consists Keep_alive_together_engraver
  }
  \context {
    \Score
    \remove Mark_engraver
    \remove Metronome_mark_engraver
    \remove Staff_collecting_engraver
  }
}

\score {
  <<
    \new StaffGroup = "winds" \with {
      instrumentName = "Winds"
      shortInstrumentName = "Winds"
    } <<
      \new MarkLine \bars
      \new Staff \winds
    >>
    \new StaffGroup = "brass" <<
      \new MarkLine \bars
      \new Staff = "trumpet" \with {
        instrumentName = "Trumpet"
        shortInstrumentName = "Tpt"
      } \trumpet
      \new Staff = "trombone" \with {
        instrumentName = "Trombone"
        shortInstrumentName = "Tbn"
      } \trombone
    >>
    \new StaffGroup = "strings" \with {
      instrumentName = "Strings"
      shortInstrumentName = "Strings"
    } <<
      \new MarkLine \bars
      \new Staff = "strings" { \strings }
    >>
  >>
}
</lilypond>

[[Category:Contexts and engravers]]
[[Category:Staff notation]]
[[Category:Included in the official documentation]]