⌂ Displaying a whole GrandStaff system if only one of its staves is alive

In orchestral scores sometimes single or groups of instruments are silent for a while and their staves can be removed for that time (with \removeEmptyStaves).

When they play again it is often preferred to show the staves of all instruments of such a group. This can be done adding the Keep_alive_together_engraver in the grouper (e.g., a GrandStaff or a StaffGroup).

In the example the violins are silent in the 2nd system and in the 3rd system. Only the first violin plays the last measure but the staff of the second violin is also displayed.