Nesting staves

The property systemStartDelimiterHierarchy can be used to make more complex nested staff groups. The command \set StaffGroup.systemStartDelimiterHierarchy takes an alphabetical list of the number of staves produced. Before each staff a system start delimiter can be given. It has to be enclosed in brackets and takes as much staves as the brackets enclose. Elements in the list can be omitted, but the first bracket takes always the complete number of staves. The possibilities are SystemStartBar, SystemStartBracket, SystemStartBrace, and SystemStartSquare.

\version "2.24.0"

\new StaffGroup
\relative c'' <<
  \override StaffGroup.SystemStartSquare.collapse-height = 4
  \set StaffGroup.systemStartDelimiterHierarchy
    = #'(SystemStartSquare (SystemStartBrace (SystemStartBracket a
                             (SystemStartSquare b)  ) c ) d)
  \new Staff { c1 }
  \new Staff { c1 }
  \new Staff { c1 }
  \new Staff { c1 }
  \new Staff { c1 }
>>