If the toggle in VEP is not working with ARIA, you might try using a Generic Remote in CuBase to enable/disable the CuBase project track instead.

Here is an example map/project that sets up an organ-stop type of configuration for my MPK2 keyboard.  Instead of using note-on/note-off over a given port/channel as I do here, you could set it up for CC events.

MPK Organ Stop Example.zip

What I mean by organ-stop, is that I can enable/disable tracks using my MPK2's MPC bank.  When I hit a pad, it lights up and arms a track for recording so it can sound/pass events.  Tap it again and the light goes out, and disarms the track (record disables).  Alternatively, I could direct the generic remote events to arm/disarm the 'monitor' button per track instead.

Depending upon your particular live setup, you might need a track for each port and channel that your project uses.  You might need local transformers to filter out things if several tracks are involved, etc.

While I've not tried it yet, there might be a way to swap out transformers via remote on the fly as well.  I.E.  Send a CC event that will have cubase toggle one of the four local track MIDI transformers off, while toggling another one on.  It might require multiple and separate Generic Remote Device maps active at the same time if you need a single event to do more than one thing inside Cubase at the same time (I call this stacked maps).

Thanks Brian. I have not yet absorbed all of the above, but re your first point, the Generic Remote setup is in Cubase. I am not aware of such a thing in VEP. That Cubase feature is totally new to me ie 2 weeks ago, but I have read as much as I can follow of many of your fine thorough posts on the subject in the Steinberg forum. 

No problem, if you have specific questions I'll do my best to answer.

In the case above, my intent is mainly to show that a way is provided through  CuBase to arm and disarm individual tracks in a project via remote control. 

When it comes to arming/disarming tracks, the track order/position does matter, so different projects that will be used with a map on on a given live performance setup will need matching track order, or multiple maps that listen for different set of MIDI events for things to work as expected.

I need the disabling of the VEP instrument channels, to leave enough power for the active instruments at any time. I would also like that action to be accompanied by the disabling of the linked Cubase MIDI track, for visual identification of enabled/disabled instruments without referring to the slave computer, if possible. I thought it would be possible in Cubase Generic Remote with a 2nd value/action for the same pedal, but the action of Disable is not offered for any target I can see.

I also looked into the Project Logical editor, but again, no applicable action.

A couple of months ago I thought I would do such things with input transformer, but have not followed through learning how to do that, as Steinberg forum posts suggest it doesn't work reliably...? If I can find good clear instruction on transformers I will look into them. At present I cant even remember where to find them. The word Transform is in the PLogical Editor but playing with that menu leaves me baffled. The whole PLE is baffling actually,. I made several series of logical selections but never found a useful way to complete them. Also, when I did make a PLE preset, I could not access it anywhere...greyed out.

Just saw your 2nd post Brian, thanks.

My Cubase project has about 200 midi tracks each routed to a VEPro instrument channel. So  just 1:1.

As I hoped, the pedal currently sends cc93 to the  VEP instrument channel linked to whatever  cubase track is armed. I would like to add another..is "map" the right word?. ..so that in addition to the instrument channel  disabling/enabling, ie dropping or picking up its samples...the cubase Midi track is Diasabled/enabled.

And then, my purpose in posting here on Garriton forum...I need GPO/Aria to be happy about the process.

MakeMusic support has told me that CC is not used in the GPO library. 

I mean, cc93