My dog...

Hi. So I have a dog. She's about a year old, pee trained, sweet, energetic, good listener, good on a leash, She's a good dog. But she's super food aggressive. This is partly because my dad has this awful beagle who is greedy, food aggressive, doesn't listen, and poops on the floor, she's 9. But, we have another amazing dog who isn't food aggressive, pee trained, sweet, energetic, good listener and also good on a leash. She is 3. I've tried all of the Ceaser Milan training things, but it's not working. We got my year old dog when she was a few months old from this awful farm where there was definitely some neglect going on. So that is also part of the problem. My mom and I have been working really hard to try and food train her, but I'm having a hard time. She's chewed six leashes. Do you guys have any tips for food aggressive dogs? Thank you :)