Heat grill to medium heat. Cut potatoes in half lengthwise and spoon out the flesh, leaving half-inch shells. Mix garlic and melted butter. Brush potatoes on both sides with garlic butter mixture.
Grill franks 7-9 minutes, or until heated through, turning occasionally; slice into rounds. Grill potatoes until crisp, about 4 to 4-1/2 minutes on each side.
Spoon sliced franks into the potato shells; drizzle with barbecue sauce and top with cheese. Grill until the cheese is melted.
Top with sour cream and chives.
Alternative cooking method: If you prefer, bake the buttered potato skins in a 250-degree oven until crisp, about 15 minutes, before adding the toppings. Fill as directed and bake 5 minutes more.