I believe I understand what you want to do. You want to put the wings in at the beginning while you are applying smoke to the ribs. Then pull them out and hold them until the ribs are ready to serve. If so you are looking at a minimum of three hours for holding the wings. The precaution you will have to take is to make sure the wings stay 140°F, or above. I'm not sure if FTC will keep them that hot for that long. You can give it a try, but monitor the temperature in the cooler.
One trick I've learned which is similar to FTC, is to use the kitchen oven as a food warmer. Preheat the kitchen oven to 250°F, put your wings in a pan and tightly foil, put them in the oven then turn it off, and keep the door closed until you want to grill the wings. That should keep the wings at a safe temperature for those three hours.
