Volume up in a Macro

I want to program a button on the Companion app (which I assume could then be used with a Streamdeck) to increase the audio volume for a particular HDMI input.

I can record a macro, but it sets the volume at an absolute level, like 20 for instance.

But what I want is to hit a button on the companion and have it increase the volume relative to what it currently is. Like add 1 or 5 to the volume.

How can I do that?

ooh that’s a good one. I can’t think of a way to do that unfortunately!