Integrating the computer just for MIDI synth editing

Running OT -> MIDI thru chain of various devices, ending up at a TX81Z that I’d like to edit via the computer (Ctrlr) while sequencing from the OT.

Before I buy a Kenton MIDI merge, is there some kind of clever workaround for this? The synth will have to be connected somehow to the computer MIDI interface’s in and out for talkback, AND receive notes from the OT.