HEAT grill to medium-high heat.
SHAPE meat into 4 (1/4-inch-thick) patties. Partially cut wieners lengthwise in half.
PLACE patties and wieners, cut-sides down, on grill; brush with barbecue sauce. Grill 4 to 6 min. on each side or until burgers are done (160ºF) and wieners are heated through, brushing occasionally with remaining barbecue sauce and topping burgers with 2% Milk Singles for the last min.
FILL buns with cheeseburgers and wieners.