Hi Chris,
With a dLive/SQ digital split, you are sharing audio, but no messaging between the SQ and dLive systems. This means that for both, you are adding 128×128 audio streams that can be used in the same way as any other input/output, many people will use tie-lines, but you could also make use of direct outs and mix external inputs.
The DX preamps will be controlled by whichever system they are connected to (there is no gain sharing), you can then patch through to the other system and use trim to adjust.
As a suggestion, and presuming you want to use the SQ for monitors: Connect the DX168’s to the DM0, then use tie-lines to patch sockets through to the gigaACE card, connect this to the SLink port on the SQ and patch inputs from SLink. Return SQ auxes to the DM0 which you can then patch these to DX168 outputs using more tie lines.
Hope this helps!
Cheers,
Keith.