Kurious Kiwi

My in-laws have a border collie-shepherd mix and she is extremely food aggressive towards my dog when we are visiting (We visit fairly often). She attacks him and will not let up when we try to stop her. She has even bitten me once when I tried pulling her off. This behavior is a recent development in the last few months (She is 2, my dog is 1 and they have been playing since my dog was 8 weeks). My in-laws and I are not sure what to do. We have tried separating them but she remains possessive of the area where her food was for a while after they are done. Last night she attacked him because he walked past the area where her bowl goes while my mother-in-law had the bowl on the counter fixing her food. We have tried feeding them in separate bedrooms and bringing them individually back into the living room and that seems to work but if he goes near the room where she ate she attacks him. She also does this for any treats. She took his busy bone once and I removed it from them, putting it in the other room and as he went to follow me, she attacked him. One change is that my in-laws have started adding canned food to her dry food due to her picky appetite. We are not sure what to do and if anyone has any suggestions it would be welcomed. She is bigger than him (he is a Bassett mix) and he never fights back when she attacks but she won't let up. Again, please help.

His mom was an Anatolian Shepherd (large breed) and his dad was an Australian Shepherd but I'm not sure how big they were exactly. I'm not sure why his legs are short.

The wires were chewed apart by my kittens... I tried re-attaching the wires but only achieved a small electric shock.