Hello Ming, It is sufficient to include the Bar_number_engraver into the \with statement of the upper Staff of the PianoStaff, as in
bar-number-staffgroup.png <http://lilypond.1069038.n5.nabble.com/file/t3887/bar-number-staffgroup.png> ChoirStaff does not need special treatment in this case: it is the uppermost stave so that the standard bar number on Score level will be OK. HTH, Torsten -- Sent from: http://lilypond.1069038.n5.nabble.com/User-f3.html
