Two computers at once. MIDI Connections: MRCC, SSP, & Ableton. USB how to do so?

[Dark Waves]

It sounds like you already have one MRCC. If so, test whether your SSP can handle the 12 virtual ports coming from the MRCC's device port, or at least work adequately for your needs before getting a second one. Disclaimer: I had never heard of the SSP before, and only half understand your objectives, so this is just a thought. I do have 2 MRCCs, though, and they integrate nicely together.