I wonder what Jon does while Richie sings one of his songs like "Stranger in this Town" or "I'll be there for you"?

Someone here said Jon leaves the stage but I have a Bon Jovi version of "Stranger in this Town" with an acoustic guitar in the background and If i remember it well Jon singing background vocals (but I'm not sure about the last). And what would "I'll be there for you" be without the acoustic guitar???

Someone of you who have seen Bon Jovi alreader might know that.

Thanks.