Nick jumped right on this one.  I’ll just add that I run two over MIDI [FCB 1010], with … really, two-plus in series [Reflex through an 8 Step Program] to the EXP input.  Works fine.  Cover the usual bases [same MIDI Channel; Output to Thru; matched CCs].  Set Expression Only the in H9 / Control app for the EXP / AUX input.

Don’t get too-too crazy with simultaneous inputs.  But that might be more of a concern to the keyboardists, contortionists, & three-footed guitarists among us.