Typically, adult children are not going to be held liable for damages caused by their elderly parents. The exception to this would be if the adult child owns the car the elderly parent was driving at the time of the crash. The adult child could be held liable for allowing the parent to drive the car if the child knew the parent was a reckless driver. This could be considered negligent entrustment.
It is important to note the victim of the crash would be seeking compensation from the liability insurance policy of the adult child. The elderly parent’s children would not be paying compensation out of their own pockets. Car insurance follows the car in Pennsylvania, so the adult child’s liability policy would cover the car when someone else is driving it.
Even if an elderly individual is a bad driver, and the children know it, they are probably not going to be held liable if they do not own the car. You could argue it is negligent for adult children to allow an elderly parent to continue driving if the parent is a bad driver. However, this is not an argument that would hold up in an insurance claim or a lawsuit.