Ok I have a little success, it appears that in Reaper, you can actually route internal input to the Halion 6 plug and then on the list where on every other software, it magically has an input, I can then route from another instrument track audio send, without ever having to enable anything or click the still elusive sidechain button, so I think the simple request is either to make the sidechain button universally available and visible on any DAW or have a configurable input so you can receive any instrument send, I am not sure about how Reaper was able to do that for me, but again I did nothing on the Halion 6 plugin because I still have yet to see a button to enable the sidechain, once I discovered how Reaper automatically did this I went back to FL studio, Protools and was unable to create a send that would be detected as an input, except in FL Studio there is one but it says it was inactive, I spent hours to try and route to it with no success.
I am looking for this to be fixed in the next update hopefully where sidechain is universal or there is an input section that you can route an vst audio send to on ANY Daw … 