Starting temporary second voice in LilyPond

Question

I'm scoring Bach BWV927 in LilyPond. For each hand, at various measures there are two voices. The left-hand second voice starts in the first measure, but the right-hand second voice starts in the third measure.

At the moment, I'm adding rests to position the right-hand second voice correctly, but I don't want its rests to appear. How do I start a voice in a specific measure?

\version "2.20"

\header {
  title =   "Prelude in F - BWV 927"
  subtitle = "Kleine Praledien Fughetten. 8"
  composer =    "J.S. Bach (1685-1750)"
}

global = {
  \key f \major
  \time 4/4
  \tempo 4 = 28
}

rightvoiceone =  {
  \relative b' {
    r16 c16 a c f,  c' a c f,  d' bes-3 d f, d' bes d |

    g,-1 e'-5 bes-2 e g, e' bes-2 e-4  f c-2 a c-3 f,  r8. | 

    r8 f' f f r8 f f f | \break

    r8 g bes g a4 r4
   \bar "|."
  }
}

rightvoicetwo =  {
  \relative b' {
    R1 | R1 | 

    r8 c a c r8 d bes d | \break

    r8 e e e <c f>4 r4
  }
}

leftvoiceone =  {
  \relative c {
    \stemDown
    f8 f8 f8 f8 r8 f8 f8 f8 | 

    r8 f8 f8 f8 f4 r16 c'16 a16 c16 | f,16 c' a c f, c' a c f, d' bes d f, d' bes d | 
    g, e' bes e g, e' bes e f c a c f, c a c |
  }
}

leftvoicetwo =  {
  \relative c' {
    \stemUp
    a8 c8 a8 c8 r8 d8 bes8 d8 | r8 g,8 bes8 g8 a4 
  }
}

\score {
   \context PianoStaff << 
    \context Staff = "rh" <<
      \global
      \clef "treble"
      \new Voice = "rhfirst"
         { \voiceOne \rightvoiceone }
      \new Voice = "rhsecond"
         { \voiceTwo \rightvoicetwo }
    >>
    \context Staff = "lh" <<
      \global
      \clef "bass"
      \new Voice = "lhfirst"
         { \voiceOne \leftvoiceone }
      \new Voice= "lhsecond"
         { \voiceTwo \leftvoicetwo }
    >>
  >>
  \layout { }
  \midi { }
}

Answer 1

What's actually going on here is that there are three voices: the top voice (right hand), the bottom voice (left hand), and a middle voice that switches between the two hands.

However, to keep your current scoring (more or less), you have two options:

1. Use \hideNotes and \unHideNotes;
   (Also, in rightvoicetwo, the capital Rs should be lowercase.)
   (LilyPond Notation Reference)

rightvoicetwo =  {
  \relative b' {
    \hideNotes
    r1 | r1 | 
    \unHideNotes
    r8 c a c r8 d bes d | \break

    r8 e e e <c f>4 r4
  }
}

2. Use s (spacer, a.k.a. "invisible rest") instead of r (rest).
   (LilyPond Notation Reference)

rightvoicetwo =  {
  \relative b' {
    s1 | s1 | 

    r8 c a c r8 d bes d | \break

    r8 e e e <c f>4 r4
  }
}