Vertical spacing question.

[Hwaen Ch'uqi]

Greetings All,

I would like to temporarily influence the vertical spacing of a piece,
idally using this form:

        \override StaffGrouper.staff-staff-spacing.padding = #5

In the NR for version 2.19.36, this type of command is shown in a
\with block, resulting in the entire score spaced accordingly. So I
thought to try the stretchability key; this improved the overall
spacing slightly, though the staves in the final system of my piece
were curiously spaced much further apart than necessary. So I moved on
to the \overrideProperty command with
NonMusicalPaperColumn.line-break-system-details and the
alignment-distances key. However, I could not find how one undoes
\overrideProperty. Or is it like \tweak, a once-and-done command?

Thank you for any advice.

Hwaen Ch'uqi