Back to normal programming 
Just completed my preliminary install with 1 x AC Combo (the Co-Ordinator), one Battery Combo and one AC Smoke Only
Here is a revised Interconnect Diagram (removing the erroneous WiFi verbiage)
The Relay Modules are hard-wired to the Co-Ordinator Alarm Module and of course these are connected to the Z-Wave sensors. I used an AC/DC box - I was able to get the two Relays & AC Connections into the AC side, but that was aided by trimming some of the HeatShrink off.
Testing by pressing the test button on one of the Satellite Modules DOES Indeed Trigger the Relay Modules Wirelessly - so the only device that actually needs physical connection to the Relay Modules is the Co-Ordinator. (Note that your Co-Ordinator MUST be an AC Module (whether it be Smoke, CO or Combo) as the Battery Modules do not have any physical connection at all.
Here is a short video showing it all works as advertised (sorry - I didn’t do any editing and the spoken
alert from the Module itself is barely audible in the recording (but fine, when it is ‘live’) - the main thing was just to show SmartThings reacting to both Alerts.
This was a fun, but also functionally rewarding project.
HUGE credit for Allan @vseven for his development work, particularly with the Device Handler Code.
Going to go ahead and add more Battery Modules to the remaining Bedrooms now. There will be a total of 7 altogether - three in halls and 4 in bedrooms (I made add another in the main family room too)