Using slashSeparator only with forced breaks?

[Jens Gyldenkærne Jensen]

Hi all. I'm trying to typeset a choral arrangement where each stanza
is set for different voices (1: SSA, 2: TTBB, 3: SSATTBB). The
handwritten original uses a separator between the first two stanzas
similar to lilyponds \slashSeparator - but in lilypond I can't find a
way to show the separator only between specific systems (e.g. after a
forced \break).

The attached image show the beginning of the score with the unwanted
\slashSeparator marks marked with red and the desired \slashSeparator
marked with green.

Are there any good suggestions to how I can make a clear visible
separation between the first two stanzas?

(I would also prefer to have the instrumentnames shown only in the
first system for each stanza)

-- 
Jens Gyldenkærne Jensen
\version "2.19.83"

2019-12-09 10_43_56-~_Dropbox_Hymnia_Noder_Glade Jul.ly [modified] – Frescobaldi.png
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