Ask your vet about medication. At least while he is going through the transition of adjusting to a new home. Doggie Prozac? He would not have to be on it forever. Once he is stable after about 6 months to a year and under the guidance of your vet taper him off and see how it goes. It’s not very expensive. They are not sedated, it just takes the edge off.
I had a dog with separation anxiety/thunderstorm phobia and this method proved to be effective.
PS: Do not feed the dogs from the same bowl, separate bowls on opposite sides of the room. Meals must be monitored. Believe me, I know of what I speak.
Do not leave food down/free feed. Food aggression is part of their personality, it will not change. Regardless of training or medication. It is a manageable condition, but you have to keep the dogs away when food is involved or children are around.
