\version "2.26.0"

bsnone = \relative c' {
  \clef bass
  \time 9/8
  \tuplet 5/4 { r8. b,, b b b } r4. | 
  \tuplet 5/4 { r8. b b b b } r4. |
  \tuplet 5/4 { r8. b b b b } r4. |
  
  R8*9 |
}

bsntwo = \relative c' {
  \clef bass \time 9/8
  R8*9*2 |
  \tuplet 5/4 { r8. b,, b b b } r4. |
  \tuplet 5/4 { r8. b b b b } r4. |
}

\score {
  <<
    \new Staff << \bsnone >>
    \new Staff << \bsntwo >>
    \new Staff << \partCombine \bsnone \bsntwo >>
  >>
}