1In medium bowl, mix orange juice, honey, chives and oil. Make cuts on top of ham about 1/2 inch apart and 1/4 inch deep in diamond pattern. Place ham in large resealable food-storage plastic bag. Pour orange juice mixture over ham; turn to coat. Refrigerate at least 4 hours but no longer than 24 hours, turning occasionally.
2Heat coals or grill for indirect heat. Remove ham from marinade; reserve marinade. Cover and grill ham over low heat 1 hour 15 minutes to 1 hour 30 minutes, brushing with marinade 2 or 3 times and turning once or twice, until heated through. Discard remaining marinade.
3Meanwhile, in 2-quart saucepan, mix barbecue sauce, marmalade and mustard. Cook over low heat 5 to 10 minutes, stirring occasionally, until well blended. Brush sauce on ham. Grill 10 to 15 minutes longer or until glazed. Serve ham with remaining sauce.