Being polite goes a long way!! Years ago before reaching Silver on NW, I flew to LAS with my mom. My mom being in her 70's, I had requested a bulkhead seat for her. Upon entering the plane, a younger gentleman was in my mother's seat. Both boarding passes said 5A. The FA had asked him politely if he would give up his seat so an elderly person could sit there. He refused and said that this was "his" seat and was not moving. He was very upset that they would assign 2 people to the same seat. FA asked for both boarding passes and took them to the GA. So here we were standing in the aisle while others went around us to board. FA came back and said that you can stay in "your" seat. She turned to my mom and said to follow her. HER seat will be 2A. That made my day.