A320 Neo - Master Battery1/2 via simconnect

OK - so, via simconnect got a lot working, but the A320 is foxing me completely
In game, the mastery battery keybind does diddly squat
The same with the EventID that works in almost all the other planes

Reading what happens when you click it via FSCUIPC - it appears to make a BUS_TO_BUS_CONNECTION_TOGGLE call

Going further, in the checklist config I can see that it says:

and

Seeming to indicate that those buttons set indeces 10 and 11?

SO - here’s where I might need a hand getting my head around it - so, hoping the wisdom of this section might be able to help.

What exactly should I be pushing in terms of the simvar side of things to achieve the same outcome via code?

FWIW, I’m working in vb.net and can call the SetDataOnSimObject and pass it info, just going round in circles working out WHAT exactly to send it (and register with simconnect).

Cheers