\new StaffGroup <<
\new Staff <<
  \set Staff.midiInstrument = "accordion"
  \key f \major
  \time 3/4
  \partial 4
\new Voice = "1" { \voiceOne \relative g' {
  c,8f | f2 \times 2/3 {a8. g16 f8} | a2 a8 g | f2 d4 | c2 c8 f | f2 \times 2/3 {a8. g16 f8} | a2 g8 a | c2.~ | c2
  a8c | c2 \times 2/3 {a8. g16 f8} | a2 a8 g | f2 d4 | c2 c8 f | f2 \times 2/3 {a8. g16 f8} | a2 g4 | f2.
  \bar "||"
} }
\new Voice = "2" { \voiceTwo \relative g' {
  c,8a | a2 \times 2/3 {c8. bes16 a8} | c2 c8 bes | d2 bes4 | a2 a8 a | a2 \times 2/3 {c8. bes16 a8} | c2 bes8 a | e'2.~ | e2
  c8a | a2 \times 2/3 {c8. bes16 a8} | c2 c8 bes | d2 bes4 | a2 a8 a | a2 \times 2/3 {c8. bes16 a8} | c2 bes4 | a2.
} }
\addlyrics {
  A -- _ ma -- zing _ _ grace! How _ sweet the sound That _ saved a _ _ wretch like _ me!
  I _ once was _ _ lost, but _ now am found, Was _ blind, but _ _ now I see.
}
>>
\new Staff <<
  \set Staff.midiInstrument = "church organ"
  \clef bass
  \key f \major
  \time 3/4
  \partial 4
\new Voice = "3" { \relative c {
  r4 | f,2.~ | f | bes | f~ | f~ | f | c' | c2
  c4 | f,2.~ | f | bes | f~ | f | c | f |
} }
>>
>>