Does each dog have its own bowl? They are dogs, not rocket scientists. Their instincts kick in before you can spit. Each dog should have its own bowl, and the same feeding times for all. A good exercise to teach them they are equal is to give them treats in front of each other and praise the dogs who don't get the treat (for non-aggression). I have 4 dogs, who eat together, and no problems like that just following these steps.