Dogs' dominant/submissive behaviors?

I think Cassie does have a bit of a dominance problem, or maybe she's just not the most respectful dog. I think what Coco is doing is she is trying to correct Cassies bad behavior. Dogs instinctively will not put up with bad behavior from other dogs and will give corrections. This helps the other dog to learn proper dog manners. You may not notice it because sometimes its very subtle but Cassie could be giving some rude looks or behaviors and Coco is reacting to it. I know this is how my dog is. She is a very submissive dog. If another dog acts aggressively towards her she will just roll over and cry. Yet she will not put up with rude behavior from other dogs. I was often puzzled by this seemingly contradictory behavior. For example one time at the dog park this puppy came running up to my dog. My dog immediately barked and growled at it and the puppy backed off. I thought, what a jerk my dog was, that puppy didn't do anything. But watching that puppy interact with another dog I realized that puppy was really rude and dominating and trying to pin down another dog. What my dog did was give a correction which caused the puppy to respect my dog. The other dog did not give a correction and the puppy took advantage of the situation. So Coco is probably a submissive dog but she still has the instinct to say 'hey cut it out'. As for the food bowl, that is a dominant behavior. Sometimes with food all manners go out the window. This is just my opinion on what you wrote. Sometimes its difficult to understand dog behavior unless you see it in person.