Duet part, rehearsal marks for both parts?

[Kenneth Wolcott]

HI;

  I'm engraving a Trombone Duet.  There are rehearsal marks.  I'd like
to engrave both parts as a score, both parts having rehearsal marks
displayed, not just the first part.

How to do this?  Lilypond 2.22.2

Thanks,
Ken Wolcott