You fail the Galaxy News Radio quest if it was not completed and Three Dog is replaced by Margaret the technician. She cannot be found in-game, making it impossible to kill her. She simply is a boring, uncaring character, compared to Three Dog's detailed, humoristic and the player's action based (bad player gets negative comments and good player gets positive comments and completed quests.) way of talking. Margaret will remain on GNR for the rest of the game.