Preheat a grill to medium high. Lay out four 18-inch-long sheets of heavy-duty nonstick foil on a work surface. Brush the foil with the olive oil (this will help the enchiladas get crisp on the bottom). Spread 1 tablespoon enchilada sauce in the center of each sheet.
Combine the chicken, 1 cup cheese, the refried beans, corn, oregano, 2 tablespoons enchilada sauce, a pinch of salt and a few grinds of pepper in a large bowl.
Stack the tortillas and wrap them in a damp paper towel. Microwave until warm and pliable, 15 to 30 seconds. Lay out the tortillas on a clean surface. Divide the chicken filling among the tortillas (about 1/4 cup each) and roll up. Place 3 enchiladas seam-side down on each sheet of foil, arranging them on top of the sauce. Spoon 3 more tablespoons enchilada sauce over each trio of enchiladas, then sprinkle evenly with the remaining 1 cup cheese. Bring the two short ends of the foil together and fold twice to seal; fold in the sides to form a packet.
Grill the foil packets seam-side up until the cheese has melted and the enchiladas are warmed through and crisp on the bottom, about 7 minutes.
Meanwhile, heat the remaining enchilada sauce in a small saucepan or in the microwave. Carefully open the foil packets and top with the warm enchilada sauce, sour cream and cilantro. Serve with lime wedges.
Cheese can stick to foil on the grill. Be sure to use nonstick foil -- and put the food on the nonstick side!