I can relate to this one. Last summer we were driving around. I was driving, my wife was the passenger driver, my 21 year old son with all the directions was in the back seat driving. I wasn't too sure what direction to take but my son insisted he knew the way. Reluctantly I went his way only to find out I was right from the beginning. All this time my wife is giving instructions of her own. My wife likes to warn the driver what lane you should be in because she gets in her lane five miles before she needs to turn. I had enough of this. I pulled off the road into an empty parking lot, got out, got into the back seat & told them to drive. Since then all I have to do is threaten to get out again & it gets silent.
You are nice and found a parking lot... I did it on the interstate.