Overlaying a texture onto a flag

Im trying to figure out the best way to go about this. I need to put multiple flag textures onto the same flag mesh. Decal isnt really working for me because I dont need opacity. All I want to do is add a texture onto the flag, and scale it down enough to get the main flag texture border. So in essence I just want to overlay the flag textures onto the main flag textures. I just cant find a simple solution for this. Since the pictures that will get overlayed are of varying sizes I need a way to scale them over top the main texture.