Well, firstly I'm not using the ST-9070 levers, I'm going to hack my own, but at this stage that isn't relevant.
Below is how I plugged everything together and it worked fine, both from the STI units and the aero shifters (hopefully the images are all visible)
When I substituted the SM-EW67A-E for the SM-EW90-A and just the aero shifters, nothing worked at all, not even a battery light on the 3-port junction box
As far as I'm aware I'm using all of the same shifting components as the complete groupset photo below:
Any assistance would be appreciated, and if I can avoid spending €163 on a PC interface or €115 on a 5-port junction when I'll only be using 3 ports that would be great!
Cheers, Rich