I have heard the same thing, only my dogs have survived many a bout with chocolate so it cannot be all THAT toxic.
Yes, chocoloate is toxic to dogs, but they have to consume a
lot of it to be harmed.
Here is an article on it from awhile back
The Straight Dope: Is chocolate toxic to dogs?
The key is that dogs tend to pig out and overeat on things like chocolate while other housepets know when to stop when they are full.
But in the end, the dog owners have no proof that the kid fed them several pounds of chocolate or that they died from chocolate poisoning. Sounds like a losing lawsuit.
And as for the chicken wings, I have never heard of anything dying from hot food. My only experience in the matter is about 5 years ago. I had a really hot plate of chicken wings on a coffee table and my sister's chihuahua jumped up, grabbed a stray wing and scurried under the bed before anyone could grab him. Ended up having a 15 second spaz/athsma attack and had his face cleaned with some wet-wipes. But before long, he was back at the table trying to grab another one.
Without any medical report that the dogs died from it, any lawsuit over the wing sauce would be similarly hard to prove.