Well, everything works now as long as I don't plug in both MOTUs.

It took some thinking and planning for wiring the patch bay, but essentially I wired things to go from any "here" to any "where".

Reader's Digest version is that I create the song on computer 1 in Real Band which is fed by the Mackie mixer for supporting instruments and vocals. When that is done I move the file to computer 2. There I assign the tracks to MOTU outs. That MOTU box is patched to 8 channels on the Mackie. That Mackie is fed back to computer 1 running Adobe Audition (my favorite software to print to) where I record it.

The patch bay also runs to and from the M-Audio interface that is on computer 1. That can be patched to either mixer, but it pretty much stays patched to the Peavey sub mixer which does nothing more than feed the house so I can hear in the room. Previously I had issues using the Mackie to add additional instruments because it was also re-recording the entire mix due to the way it was all pathed.

The Mackie also has 3 Alesis Midiverb 2 effects bussed on three of the aux sends so if I choose to I can assign different reverbs to different instruments. Maybe one for drums, another for vocals, a third for anything else....

It probably sounds more convoluted than it would be if you saw it, and I don't know how I would take pictures of "logic". Pictures would just show all the hardware. The patch bay is the key.

Bottom line is that the pretty green lights flash on the MOTU as data passes through them, which makes the pretty green L&R lights flash on the Mackie, which makes the pretty green lights on the M-Audio interace flash, which gives me squiggly line waveforms in the Adobe Audition, all coming from the pretty wave forms in the Real Band software.

Now, as to why that second MOTU freaks Real Band out, I still have no clue. And seeing as I rarely exceed 8 tracks (and when I do, I can share the tracks because if I get to that many tracks it is because there are either extra harmony tracks, extra drum fills, 2 instruments trading solos, etc...) I no longer care that the second box doesn't work. I will just not use the second box and maybe sell it off. Or keep it as a spare.