Thanks, ioTon; your response is super helpful indeed.
For clarification purposes, I am in the market for a digital mixer and currently debating over Midas M32R Live or Allen & Heath SQ5.
With your guide, it seems that I should be able to use XLR Out 9 and 10 to send the mixed signal to Fusion and return the processed signal via ST1 using balanced cables (to save XLR inputs), where it’s then routed back to the main mix. Using the same technique, I should (in theory) be able to patch in my Lexicon MX400XL (XLR Out 7,8 => ST2).
I hope I am making the right choice with SQ5.