It's kind of hard to parse out exactly what you want to do. Sounds like you want the sound system to be interchangeable between the two TVs, get the headset in on the mix, as well as everything seamlessly turn on and off simultaneously. You'd probably need more than a Harmony remote, and need some kind of controller (like an iPad or Android tablet, or a dedicated one.)
Don't believe everything on the Interwebz! A duck's quack DOES echo!