As I previously posted (thank you for those CVG ideas!), my parents will soon be flying Delta and Delta Connection - TOL-CVG-LAS. Is it possible for my parents to use their NW WorldPerks numbers for mileage credit, instead of DL SkyMiles? Of note: 1. They belong to both programs. 2. Their itinerary is coded with DL flight numbers. How does that all work? Blaine Thompson Fort Wayne, Indiana