Do you need this MRCC accessory?

[Dark Waves]

Wait… so I can connect mrcc 1 to mrcc 2 via USB
I can then still connect mrcc 2 to DAW and connect the 7 to mrcc 1
mrcc2 (or daw) can then reach mrcc1 via 1 usb channel, so if everything on mrcc1 has a unique midi channel, things are good. Is that a correct understanding?

The extension via USB is a device in development that will allow 4 extra DIN inputs to one of the 4 USB host ports.  It's described on the CL home page, bottom right.  Those USB ports can handle 4 in and 1 out, so connecting a second MRCC there wouldn't be a match, if functional at all.  Another little device they're working on is an adapter so you can combine 2 MRCCs with a Remote 7 using ethernet cables.  It's also described in that same section of the main site

In the meantime, there's an option worth considering: if you connect both MRCCs (or even more, I'd imagine) directly to the computer, or via USB hub, you can use your DAW to route between them without the need for the ethernet connection, and then you can use the Remote 7 via ethernet as additional ports, so long as you don't mind giving up the direct / offline cross-unit routing.  In my setup, until the adapter becomes available, I have the 2 MRCCs connected both to my PC on USB hubs, and to each other with ethernet, so I can use my keyboard sequencer out of the box without the DAW, or with it, either way, and my Remote 7 is waiting to be connected until I can get an adapter.