The complexity of the solution depends on the complexity of the situation.
You appear to be wanting to use the Monomachine and your DAW as your main sequencers. Do you want to gave the DAW and the MM running at the same time in sync, or do you only use them separately?
If the MM and DAW are the sequencers, there is no sense in anything else providing the master MIDI clock source.
What model is your master keyboard? Is there any reason why you couldn’t use the Sub37 as the master keyboard?
What are your other MIDI synths?
Depending on your answers there is likely an easy way to realize your desired system with your existing gear, although if you want more flexibility it might well be useful to get a better MIDI interface (as others have suggested).