still no ultimate way to create three-staff piano layout

[Karol Majewski]

It seems that there is no ultimate way to create three-staff piano layout.

When typing solo piano piece, there is no problem. The following does the job:

\score {
  \new PianoStaff \with {
    \remove "Keep_alive_together_engraver"
  } <<
    \new Staff = "right" \right
    \new Staff = "left" \left
    \new Staff = "leftExtra" \with { \RemoveEmptyStaves \override 
VerticalAxisGroup.remove-first = ##t } \leftExtra
  >>
}

The question is: what if three-staff piano is part of orchestra? In orchestral 
score, when piano is "tacet", the whole PianoStaff should be removed from the 
page.

Adding \RemoveEmptyStaves to every Staff is a bad idea, because when the 
"right" staff has some nmusic and the "left" staff is empty - only the "right" 
will be shown (And I want the "left" to be shown also!) 

\score {
  \new PianoStaff \with {
    \remove "Keep_alive_together_engraver"
  } <<
    \new Staff = "right" \with { \RemoveEmptyStaves } \right
    \new Staff = "left" \with { \RemoveEmptyStaves } \left
    \new Staff = "leftExtra" \with { \RemoveEmptyStaves \override 
VerticalAxisGroup.remove-first = ##t } \leftExtra
  >>
}

So, is there any way to create such layout? Maybe it's possible to:
1) remove single Staff from PianoStaff without removing 
"Keep_alive_together_engraver"?
2) make "Keep_alive_together_engraver" to keep alive only two highest Staves in 
PianoStaff?

-Karol