My sister is 23, in college, and still on my parent's car insurance plan. She was letting her boyfriend drive her car and they totaled it. One of the passengers in the car was not wearing his seatbelt, was thrown from the car, and is injured very badly. There is no law in Iowa that says he had to have a seatbelt on since he was in the back seat. My parents have insurance on the car, but I am afraid this kids hospital bills will exceed the insurance. The driver of the car (my sister's boyfriend) does not have any insurance to help cover the expenses. Can the injured passenger come after my parents for their personal assets also despite the fact they had nothing to do with the car accident? Thanks

OK I'm in the UK so I'm not sure how good this advice will be.
In the event of an accident then THE DRIVER of the car is liable,
In this case it was your sister's boyfriend, so he's in the firing line.
It is up to him to arrange insurance cover on any car he drives and so he is completely liable for this.

Why haven't you talked to your insurance agent? They can tell you what the policy covers.

However, there is a likelihood that they can come after your parents if they owned the car. But only if they owned the car. In the US, many policies are written to cover authorized drivers only. So the insurance might not cover the boyfriend. However, if they were to be sued a jury would award damages on a percentage basis. So they are unlikely to be hit too hard.