Edit: see the suggestion by @charles_piano here:
I leave my previous workaround, that maybe can be useful for other cases, as this, for example, where the OP doesn't want brackets on the vocal staff
Hi @k.k, in Notation Options>Barlines you can set all the end system barlines to join all staves (but is probably not what you want):
If you want the join only in that specific place you can use a workaround:
create a new vertical barline, with a new body, made by a double line with appropriate settings:
Then create a Coordination Line at the barline previous to the double barline (selecting both barlines of S and A) and clicking Coordination Line in Engrave mode, and assign to it the newly created “double” line as Line Style in the properties panel. Position the line as needed:
Result:
Dorico file example:
coordination line as join.dorico (1.4 MB)