Virtual Masters with Smart Components in a variable font?

I have a variable font with a smart component (with one property) used in many glyphs. Now I want to add a Virtual Master to affect that component and having a variation axis for that.
I could add a second smart component property, but the idea is to make this variation accessible for the user in the variable font. The problem is that I don’t know how to make smart components and virtual masters work together, since both are done through layer copies.
Is this possible? Or is there a way to link a second property of a smart component into a variation axis?

This screenshots explain better my problem:
When I create an intermediate layer in a regular glyph, I can access the Variation Axes:


However, when I do the same in a Smart Component, I only see the Smart Glyph’s Properties, no access to the Axes.

Technically, I could work around this by creating a new master and modifying the Smart Glyph accordingly. But I wonder if there is a way to use intermediate (virtual) masters within Smart Components without needing extra masters?

The smart glyphs can’t respond to font axis in a variable font. In a setup like this, you need to add a brace layer in each glyph that uses that smart component.