PREHEAT barbecue to medium-low heat. Mix barbecue sauce and drink mix until well blended. Place half of the ribs each in single layer in centre of sheet of heavy-duty aluminum foil. Spoon sauce mixture over ribs.
BRING up foil sides. Double fold tops and ends to seal packet, leaving room for heat circulation inside.
PLACE packets on grate of barbecue; cover with lid. Grill 1 hour and 30 min. or until ribs are very tender. Remove from foil. Skim fat from sauce and serve with ribs.