Placement of melisma dashes when spanning more than one line

Unless I am missing something, if a melisma spans across several lines, as it does in the attached carol, Ding dong merrily on high, the offset spacing continues between lines, when I don't think it should.

Observed behaviour:

You can see the long syllable, "Glo". This spans across three systems. I would like to offset the syllable and the dashes on the first system to be roughly centred between the two staves. If I do so the dashes on the second system inherit the same offset, as shown here:

Expected behaviour:
I feel I should be able to change the offset of the dashes on different lines separately, so I can achieve the first system looking as it does in the second image, but the second system looking as it does in the first image.

I appreciate this is a niche requirement, but it's one of the few things I've not found a way round on MS4.