Yikes. My bad. Somehow misread that.
Thats harder than I thought since the relative construction methods are somehow not available when making guidelines.
Anyway, a workaround would be to just use normal lines at first (since you can use the relative methods on them), and then use the orange guidelines, if you want them to persist.
If you just need them temporarily I'd go with the blue snap guides instead.
Mostly AC 26 on Mac | Author of SelfGDL | Developer of the GDL plugin for Sublime Text
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