MC3 connectivity to HX stomp and Macbook?

Morningstar MC3 occupies one MIDI/USB input in the HX stomp.
The second MIDI/USB in/out of the stomp is occupied by a Yamaha wireless midi transmitter.
Additionally I would need a third MIDI/USB in order to connect HX stomp to my Macbook to use HX stomp Edit Software. But there is no third MIDI/USB in the stomp.
Is there a way to connect HX stomp to my Macbook via MC3?

The only Midi in for the MC3 is through the USB port, which it sounds like it wouldn’t work for you with your wireless transmitter. I need to have a standard midi input so I have the MC6. There is such a thing as a midi merger, such as from Quadra Solutions. I tried it to combine two different midi inputs. I wasn’t happy with it as you need to get 5V power over the midi pins, and not 9V. The way you want it is to have a proper chain somehow. What about Macbook at the top connected through USB? Wouldn’t the MacBook send commands/midi instead of receive it? Good luck!!