J'efface tout, la solution est beaucoup plus simple :
%%%%%%%%%%%%%%%%
aigues = \relative c' {
\time 6/8
s4.
\stemDown
c16[ bes' e]
\stemUp
g c e
\stemDown
g8
}
basses = \relative c {
\time 3/4
\clef F
\override TupletBracket.positions = #'(4.5 . 9.5)
\override TupletBracket.edge-height = #'(1 . -1)
\tuplet 7/6 {
c16[ bes' e]
\change Staff = md
\stemUp
g[ c e g]
}
s4.s8
}
\new PianoStaff
\with { \omit TimeSignature }
<<
\new Staff = md \aigues
\new Staff = mg \basses
>>
%%%%%%%%%%%%%%%%%%%%
Pierre