Winnebago used a BIRD/BCC system in the Ultimate Advantage. It will charge the house batteries and engine battery from the converter and the engine battery and house battery from the alternator. The only model it was ever used on as far as I know.
They usually use a continuous duty solenoid that is activated by the run terminal on the ignition switch to allow the alternator to charge the house batteries when the engine is running. With the standard/usual system the house converter does not charge the engine battery.
I would call Winnebago and ask them about it.