Who owns most taco bells?

Taco Bell belongs to Yum! Brands, who also owns A&W, KFC, Pizza Hut and Long John Silver's. Yum also has WingStreet, who they claim is the world's largest chicken wing delivery company--but all WingStreets are colocated with Pizza Huts, so is WingStreet an actual brand, or just their trade name for chicken wings?