Thanks, Keith.
In any relationship, and particularly in a blended household, you have to be very careful picking your battles. The Alpha Male approach - which appears to be the modus operandi of many posters here (Porsche forum: who'd have thunk?) - can be caustic.
Room Monkey # 1 has a strong personality. A near-classic Alpha Male & therefore he has always required handling in an atypical way. Direct confrontation has never been effective. A flanking maneuver has historically been far more successful. You have to know your enemy - or in this case family - and plan accordingly. Often letting him think he has won the battle, let's you win the war.
Ian