Hey David,
Thanks for responding. I went ahead and threw caution to the wind, and plugged every conceivable inputs to outputs, and Visa versa configuration from both mixer and DP. (When the fire department finally extinguished the blaze) I decided that wasn't a good idea.
Kidding!....
Anyway after finally finding a path and signal from mixer into DP I got sound, but it sounded kinda weak. I kept at it, and succeeded. When I went the opposite direction to see what would happen I got mixed results. I wanted to see if I could create a path from the DP to the mixer, to the computer to my DAW using the mixers interface, and surprisingly I got signal to the DAW, and it recorded, but I couldn't get any actual sound for some reason, until I reconnected my Focusrite 18i8, and then the sound found its way out. I'm not sure yet what, if any application this path would be usefull for, but I'm trying now to find what I did, or didn't do to block the signal to my monitors. Next up DP to Mixer (it's interface deactivated) to Focusrite Interface to DAW.
This info is probably making y'all yawn, but it was a leap forward for me to overcome my anxieties over gear damage. Take care...