Possible to combine two MIDI assigned inputs for a third output?

I’d love to know if there’s some trick to combining two assigned MIDI inputs (like, say, FX button with jog wheel) that when used at same time do something unrelated to either input (like adjusting FX level or FX dry/wet amount).

I notice in djay Pro AI (v3.0.7) in Mac OS (Big Sur v 11.2.2), I can access MIDI settings and output for one or the other inputs but can’t find a way to combine them into a third output.

I think the right term for my request is MIDI modifiers as described here: