Need Advice - Refrigerator on separate Inverter

I think I figured out my question on how that Fridge Battery is connected to the front two coach batteries. Where the + wire going from the Fridge Battery to the Generator connects to the Gen, is also the + large gauge wire that comes back to the Gen from one of the Solenoids up front. So I believe that explains how they are all tied together. Below is a pic where both come together at the Gen.