It should. If I'm not mistaken, there should be a relay called "BIRD" Bi-directional Isolation Relay Delay. You could check to see if your buddy has one in his coach.
You could put a multimeter on the house battery and measure the voltage with shore power disconnected. Start the engine and watch for the voltage to increase to about 14v. If it does, the engine is charging the batteries.
2000 Cherokee 29BH with 6V batteries, LED lights & 400 watts of solar power, flipped axles and raised. 2007 Tundra 5.7L DC-LB with lots of mods. C-co, 8/158th AVN Maint.