Custom ambitus ?

Hi everyone,

Is there a way to inject specific notes in the "Ambitus_engraver" ? I
guess then it would be trivial to gather all the different notes in a
music expression.

Take this timpani example :

\version "2.27.2"

\new Staff \with {
  instrumentName = "Timpani"
  \consists "Ambitus_engraver"
  \clef bass
} {\key d \major cis f g b}

\new Staff \with {
  \omit Clef
  \omit TimeSignature
} {
  \omit Stem
  \clef bass
  <>^"↓Expected ambitus"
  <cis! e! f! b!>4
}

Thanks for pointers on the subject :-)
-- 
Pierre-Luc Gauthier