\version "2.21.0"

music = \relative c' {
  \mark \default
  c4 d e f g a b c
}

someGroup = \new StaffGroup <<
  \music
  \music
>>

\score {
  <<
    \someGroup
    \someGroup
    \someGroup
  >>
  \layout {
    \context {
      \Score
      \remove "Mark_engraver"
    }
    \context {
      \StaffGroup
      %\Staff
      \consists "Mark_engraver"
    }
  }
}