Positioning opposing fermatas on a bar line
This snippet demonstrates a command that prints fermatas both above and below a bar line. If there would not otherwise be a bar line, it adds a double bar line. Semantically, the command codes a longer-than-normal caesura, which might be considered misuse depending on the situation.
twoWayFermata = { \once \set Staff.caesuraType = #'((underlying-bar-line . "||")) \once \set Staff.caesuraTypeTransform = ##f \caesura ^\fermata _\fermata } music = { f'1 \twoWayFermata R1 f'2 \twoWayFermata f'2 R1 b'1 \twoWayFermata \fine } \new GrandStaff << \new Staff \music \new Staff \music >>