Question about an Instance issue

I was wondering if someone could advise me on an issue I’m having with an instance.
Here’s my situation. I have a typeface that has two masters (Light and Bold). I have a single instance (Regular) that is being created by an interpolation of the Light and Bold masters.
I have certain features in the letterforms of the Light master, that I don’t want in the Bold master, but that I DO want in the Regular instance.
I’m familiar with “bracket trick”, but it doesn’t seem to apply to this particular issue.
Using a dollar sign as an example, let’s say I want the vertical bar to cross through the dollar sign in the Light (master) and Regular (instance) but in the Bold (Master) I only want it to extend above and below the s-shaped part. Because my Regular weight is an instance, I can’t input a “bracket trick” layer to tell Glyphs that masters above that weight should reference a different layer.
Sorry if this is confusing, but I was hoping someone would have some advice for me.

If you do implement the bracket-trick in the black-master (a striked through dollar), you can interpolate the targeted shape for the regular (light-to-blackbracket) and still export the blackmaster

Or use

Thank you! I think this link has the info I needed.

This dollar stroke is what the bracket trick is meant for.
Your regular masters have the one stroke. Then you copy both masters and remove the middle part of the stroke. Then you add the bracket name to the new layers an you are done.