They could be added anywhere, in the same order that you specified. Since these commands would be specific to a single device, they would logically be grouped w/ other commands for that device. If they wanted to implement this and go the extra mile they could even prompt for placement. The bottom line is, that the feature would allow you to take advantage of it if you wanted to without impacting users that have no interest in propagated commands.

Essentially, Logitech went from one extreme to another, leaving some satisfied and some disgusted. The fact that they dropped propagation for everybody rather than trying to accommodate those that want it and those that don't seems to be the worst solution they could have implemented. The current implementation does not satisfy me one bit so I'd like to see any feature implemented that gives me more control not less.