Inter-staff bar line for ChoirStaff?

[Matthew Fong]

Dear LilyPonders,

I'm using ChoirStaff to typeset some SATB vocal music, but for clarity to the singers, I wanted to extend the double bar so that it is also in between the bar lines. The ChoirStaff doesn't allow this per LilyPond documentation (https://lilypond.org/doc/v2.23/Documentation/notation/displaying-staves#grouping-staves).

I found this code from a few years back, but it doesn't seem to work for 2.22.2.

https://lists.gnu.org/archive/html/lilypond-user/2012-10/msg00088.html

Would anyone have a way to accomplish this?

Many thanks,

mattfong