MIX barbecue sauce and marmalade until blended. Place meat in slow cooker; top with barbecue sauce mixture. Cover with lid.
COOK on LOW 8 to 10 hours (or on HIGH 4 to 6 hours). Remove meat from slow cooker; cut into small pieces or shred with fork. Return to slow cooker; stir until meat is evenly coated with sauce.
SPREAD Miracle Whip onto cut sides of buns; fill with meat mixture.