We need 3 monitor systems, but the desk has only 2 that are fully mixable from what I can make out.
Here's what has been suggested to me to overcome the problem. You have to assume that bass and guitar will have small speakers on stage for own monitoring.

The drummer gets the in-ear and the keyboardist gets monitor two.
It's what we need to do to get monitor 3 and 4 mixable signal to the singer, guitarist and me that's the burning question.
It has been suggested that the "auxilliary" be either the EFFX sends one or two.
Does anyone have any experience with this desk and/or can point me in the right direction as to either how I configure it or what else I could buy to make mixing for 3 & 4 much easier.
Many thanks