The normal ET 8 would be perfect to control the pool and Spa as one body of water and has the ability to switch back and forth between the Pool mode and Spa mode, as well as run in the Spillover (Spillway) mode. Switching between the pool and spa is a built in function, so very easy to set up... the key is to have the Intake Valve and Return Valve set up as my crude drawings show..
I was reading the EasyTouch manual today. There is a "Fill / Spillway" valve position which is supposedly only available in the service mode.
There is also a preset circuit function called "Spillway" which pulls water from the pool and returns to the spa. I assume that this is different than the above "Fill / Spillway" which is only available in the service mode?
Specifically - can I program a "Spillway" function to one of the Aux buttons and program it to run in the "Auto" mode?