Lilypond: How to create an ossia Staff above a PianoStaff?

Question

When trying to create an ossia Staff, that is used multiple times, above a PianoStaff, Lilypond does not reuse the context, but creates a new one. How can I tell Lilypond to find the existing context outside the PianoStaff?

\version "2.20.0"
<<
  \new Staff = "ossia" \with {
    \remove "Time_signature_engraver"
    \remove "Clef_engraver"
    fontSize = #-3
    \override StaffSymbol.staff-space = #(magstep -3)
    \override StaffSymbol.thickness = #(magstep -3)
    %alignAboveContext = "left"
  }
  { \stopStaff s1*5 }

  %\new PianoStaff = "piano" \with { instrumentName = "Piano" } % <<< if I add this, it does not find the context anymore
  <<
    \new Staff = "right" \relative {
      c'4 b c2
      <<
        { e4 f }
        \context Staff = "ossia" {
          \startStaff e4 e8 f \stopStaff
        }
      >> e2
      g4 a g2
      <<
        { g4 a }
        \context Staff = "ossia" { 
          %\change Staff = "ossia"
          \startStaff g4 e8 f \stopStaff
          %\change Staff = "right"
        }
      >> g2
      e4 d c2
  }
  \new Staff = "left" \relative { \clef F c1 c c c c }
  >>
>>

Without PianoStaff:

With PianoStaff:

Note: I also tried to add the ossia Staff inside the PianoStaff: that works for the ossia staff, but it centers the name of the instument wrongly:

Answer 1

Does this work for you?

\version "2.20.0"

\new PianoStaff = "piano" \with {
  \override InstrumentName.extra-offset = #'(0 . -4)
  instrumentName = "Piano"
} <<
  \new Staff = "ossia" \with {
    \remove "Time_signature_engraver"
    \remove "Clef_engraver"
    fontSize = #-3
    \override StaffSymbol.staff-space = #(magstep -3)
    \override StaffSymbol.thickness = #(magstep -3)
    %alignAboveContext = "left"
  }
  { \stopStaff s1*5 }

  <<
    \new Staff = "right" \relative {
      c'4 b c2
      <<
    { e4 f }
    \context Staff = "ossia" {
      \startStaff e4 e8 f \stopStaff
    }
      >> e2
      g4 a g2
      <<
    { g4 a }
    \context Staff = "ossia" {
      %\change Staff = "ossia"
      \startStaff g4 e8 f \stopStaff
      %\change Staff = "right"
    }
      >> g2
      e4 d c2
    }
    \new Staff = "left" \relative { \clef F c1 c c c c }
  >>
>>

Answer 2

since I use ossia in piano scores for left and right hand, the only solution I found works with markup only

\version "2.20.0"


\include "english.ly"

#(set-default-paper-size "a4")
#(set-global-staff-size 14)



staffUpper = {\change Staff = RightHand}
staffLower = {\change Staff = LeftHand}


global = { %\easyHeadsOn
  \key c \major
  \numericTimeSignature
  \time 4/4
}

RHI = \relative c' {
  \voiceOne
  \global
  
  c4 d e f
  c4 d^\markup{\hspace #-12
             \score {
    \new Staff \with {
      \remove "Time_signature_engraver"
      \magnifyStaff #2/3
      firstClef = ##f
    }
    {\clef bass \relative c {\partial 1 c4 d f e f }}
  }} 
   e f
  c4 d e f
 
  
}  

RHII = \relative c' {
  \voiceTwo
  \global
}

LHI = \relative c, {
  \voiceThree
  \global

c4 d e f
  b,4 d4 e_\markup{\hspace #-12
             \score {
    \new Staff \with {
      \remove "Time_signature_engraver"
      \magnifyStaff #2/3
      firstClef = ##f
    }
    {\clef bass \relative c {\partial 2 c4 d f e f }}
  }}
  
     f
  c4 d e f

}

LHII = \relative c' {
  \voiceFour
  \global
} 


Dynamics = {
}


\score
{
  \new PianoStaff \with {
  }
  <<
    \new Staff="RightHand"{ \clef treble
    <<
      \new Voice = "RFirst"
      \relative c'
      \RHI
      \new Voice= "RSecond"
      \RHII
    >>}
    
    \new Staff="LeftHand" { \clef bass
    <<
      \new Voice = "LFirst"
      \relative c'
      \LHI
      \new Voice= "LSecond"
      \LHII
    >>}
  >>
  \layout { }
  \midi { }
}

Output:

Answer 3

Whenever there are many such staves (for example to show the notes below a ChordNames staff), I placed a mix of the code from other answers in a Scheme function, and used it in a lyrics staff:

#(define-markup-command (chordstaff layout props notes) (ly:music?)
  (let ((markup #{ \markup {
                     \score {
                       \new Staff \with {
                         \remove "Time_signature_engraver"
                         \remove "Key_engraver"
                         \remove "Clef_engraver"
                         \magnifyStaff #3/4
                       }
                       { #notes }
                     }
                   }
                #}))
        (interpret-markup layout props markup)))

\score
{
  <<
    \new Staff { c'4 e'4 g'4 e'4 | c'1 }

    \new ChordNames {
       \chordmode { c2 | g2 | c1 }
    }

    \new Lyrics {
      \override LyricText.self-alignment-X = #LEFT
      \lyricmode {
         \markup{\chordstaff{<c' e' g'>2}}2
         \markup{\chordstaff{\partial 2 <b d' g'>2}}2
         \markup{\chordstaff{<c' e' g'>1}}1
      }
    }
  >>
  \layout {}
}

Output: