Instrument Names for Staff Groups?

[Orm Finnendahl]

Hello,

 I'm trying to typeset a piece for 4 Percussionists. Each of them will
use 4 \Staffs combined into a \StaffGroup: 2 percussion staffs and a
combined bass/treble \PianoStaff for Mallets. I would like to have the
name "Percussion 1" printed in front of the whole group, vertically
centered and always printed throughout the score, even if some staffs
are removed with the \RemoveEmptyStaffContext if they don't contain
anything for some systems. Does somebody know about a way to
accomplish that? I couldn't find anything in the docs or LSR (I also
checked orchestrallily to no avail).

I tried

\set StaffGroup.instrumentName = \markup \left-column { "Perkussion 1" }

but that doesn't print anything (although it doesn't complain
either). Below is the code for one of the four percussion players with
the name assigned to the top staff.

Thanks in advance for any help.

--
Orm

\version "2.13.23"

poneone = { {
  f4 a c' e' g'
} }

ponetwo = { { 
  f4 a c' e' g'
} }
ponethreeup = { \relative c' {
  c4 e g b d 
} }

ponethreedown = { \relative c {
  g b d f a
} }

\score {
 \new StaffGroup { 
   <<
     \new Staff = poneone {
       \set Staff.instrumentName = \markup \left-column { "Perkussion 1" "" }
       \set Staff.shortInstrumentName = \markup \left-column { "Perk. 1" "" }
       \clef percussion \poneone
     }
     \new Staff = ponetwo {
       \clef percussion \ponetwo
     }
     \new PianoStaff { <<
  \new Staff = ponethreeup {
    \ponethreeup
  }
  \new Staff = ponethreedown {
    \clef bass \ponethreedown
  }
    >> }
  >>
 }
 \layout {
   indent = 4\cm
  \context { \RemoveEmptyStaffContext }
 }
}