Are you sure this is caused by pack order? I mean, look at the wolves. A single wolf will definately growl at, and even to some degree fight against, the alpha to protect its food WHEN HE HAS THE FOOD IN HIS MOUTH. This is a law in the wolf world. If there's a prey or a dead animal on the ground then the alpha shall eat first, and if anyone else attempts to sneak it will be a horrific fight. However, if a wolf ALREADY has the food in his mouth, then the alpha will usually not take it away from him/her. So it's perfectly fine if your German Shep. mix defends its food when he's eating, and it's not necessarily a sign that he tries to be alpha. But let's say that you drop a peace of meat on the floor 2 meters infront of both dogs. If your German shep then tries to fight with your alpha dog before reaching the meat...then he tries to achieve alpha The same applies to my dog.....I can say "no!" if he attempts to steal food and then he gives up without growling. He accepts that I'm alpha and that I should eat first. However, If he's already the food in his mouth he'll fight to protect it. In these situation I do like the alpha wolf....I let him keep it.