what kind of car insurance and for who

Hi I'm trying to figure out who needs to get insurance on a car and for how much? Ok I inherited a car-that I am not going to drive (its a straight drive) I know I should just sell it but I don't want to yet. I think I am either going to let my boyfriend (30 years old) or my little bro (18 years old) drive it or possible they can share. It is a crappy car but it gets good gas mileage. I now have a lot of assets I need to make sure are protected...ie if they get in a wreck I don't want to be sued. Both boys will dog this little car, I don't trust either one of their driving. However, I think just sitting in the driveway probably isn't good for it either. What people need to be insured and what limits should I get. I have my own policy, my boy friend has his own policy and my little bro shares a policy with my mom and step-dad