If the inverter sees A/C power coming in it should bypass and not be in the mix. There are settings that will tell it when it needs to comes on. According to the GT7 brochure, it's a 2000w Magnum inverter, same one I have. I don't have a MultiPlex system in my 2014 coach but I'm guessing you have another panel specific to the inverter. I keep the inverter on all the time so when I unplug from shore power, everything 120v stays on uninterrupted save the A/C units. This way I don't have to reset the clock on the micro. Also all the network gear in the coach stays powered and doesn't drop any connections.
2014 Sportscoach Cross Country, 361BH