Hymn template for per-voice music and \partcombine

When writing hymns it is desirable to keep each part (soprano, alto, tenor, bass) separate. But when using partcombine to combine the parts, there are some difficulties. This template works through the difficulties and provides a useful method of writing hymns in four parts, then combining the upper voices and the lower voices.

\version "2.24"

%% http://lsr.di.unimi.it/LSR/Item?id=653
%% see also http://lilypond.1069038.n5.nabble.com/LSR-v-2-18-quot-Hymn-Template-for-per-voice-music-and-partcombine-quot-does-not-compile-tc159367.html

%LSR by Carl Sorensen on Jan 19, 2010.
%LSR modified by Ed Gordijn on Feb.2014 for v2.18

soprano = \relative c'' {
  a4 a c b
  c a' g f
}

alto = \relative c' {
  c4 \partCombineApart \override NoteColumn.force-hshift = #1.7 
     a' c b
  c4 a' g f |
}

tenor = \relative c' {
  g4 g g d
  g4 d d g
}

bass = \relative c {
  d4 d d \once \partCombineApart d
  g, g g \once \partCombineApart g'
}

verseOne = \lyricmode {
  \set stanza = #"1."
  This is verse one
  It is more fun
}

verseTwo = \lyricmode {
  \set stanza = #"2."
  This is verse two
  It's good for you
}

\score {
  \new ChoirStaff <<
    \new Staff {
      \key d \major
      <<
        \new NullVoice = "aligner"  \soprano
        \new Voice = "upper" \partCombine \soprano \alto
      >>
    }
    \new Lyrics \lyricsto "aligner" { \verseOne }
    \new Lyrics \lyricsto "aligner" { \verseTwo }
    \new Staff {
       \key c \major
       \clef bass {
         \partCombine \tenor \bass
       }
     }
  >>
}