As I said, all your devices have discrete codes available. If you program your remotes to use them, that will solve your problem. There is no need for state swap or shielding. Try the logitech forums if you need more details. The techs and other users there seem to have more knowledge than the rep that helped you via email.

Here's the big picture of how I would handle this:

- Go through device setup for each device and specify that each uses separate commands for on and off, as I said before
- Optionally add additional commands to the start of each activity with redundant discrete on commands to cover cases where your second remote would have turned things off (this may require learning dummy on/off commands from your other Harmony)
- Create an activity that turns everything off