Thanks Yutaka,
$n seems to work great. Is it possible to implement named groups for Find and Replace, if the engine used is Onigmo? From the documentation (https://github.com/k-takata/Onigmo/blob/master/doc/RE), it seems as though it is supported?
e.g: Section 8. Backreferences
\k<name> \k’name’ backreference a group with the specified name