Sorry Norm K but I think you have it all apex over base re current flows and connection points. As it is wired is perfectly fine, current will flow into the batteries if their voltage is lower than the alternator output no matter where the connection is made. 50 years as an electronics technician working on everything from fighter jets to stand alone solar power systems tells me it is so.
One thing though, the wire being used is way too small for 50 amp draw. AVB is right that the batteries need to be isolated from each other. Apart from fuses which would hae to be quite high current anyway given the charge current, a diode in each charge input wire will stop them from feeding back to the other battery if one gets a short.
