I am looking to do a model variant of an existing aircraft, including built in aux tanks that a real world variant of an aircraft has. These are NOT ferry tanks, but extra tanks built into a wing void on a real aircraft. I have the IRL weight and balance data and fuel tank capacity, but need help making it work on MSFS 2020. I knew hot to do it up to FSX years ago, but the newer version is a bit different. How do I add the tanks and make them work properly?