mac76

We recently rescued a 1 year old chocolate lab named Griz from a lab rescue group. Unfortunately Griz spent his whole first year in a shelter and a foster home. We have had Griz for about 2 months now and he has been a handfull but terrific dog.
We have two other dogs;a Vizsla that is 5 and chocolate lab puppy that is 4 months. He had little to no training at all. He is very aggressive with his toys (which we are working on) and recently has become aggressive with food towards Jazmin (Vizsla). The first time it happened we had to leave them in our vets kennel for the weekend and the tech fed the two at the same time (as we do at home). Griz attached Jaz for her food. We thought it was "kennel syndrome" but then he has done it since then. I have been watching to see if Jaz provokes him but she doesn't.
He gets done with his food first and then grabs her and flips her on her back as if his is attacking her for the food.It is very scary. I am very conserned about this and unsure what to do.Can anyone help me out?