ANSWER
First, your brother's car should be insured anyway. However, if you have your own insurance policy and this fact is stated in the policy, you are liable. Furthermore, if you by chance, reside with your brother, you should be included in his policy. If your brother's coverage is liability only, but your's is higher, the higher coverage may apply, however, 2 policies on one vehicle may be applied in case there are excessive damages and/or personal injuries. In any case, all damages need to be satisfied based on the policy (s) limits, and that's if the other driver's insurance co. requests policy limits verification.
Only if the crash was a result of a mechanical defect in the car, and you knew of the defect before loaning the car to them. If the crash resulted from their actions while driving (or another person's), you are not liable. If the person driving your car was at fault, you will be responsible for any damages.
The person that is responsible for the accident.
The owner of the car is liable for the accident itself and the damage. However, the insurance company might have to pay for it, depending on the owners insurance cover.
The fault lies with the vehicle that cause the accident. When someone borrows a car, the car owner can be liable because the allowed someone to drive the vehicle. Often this type of accident has to be sorted out in court.
Who else do you think should be held liable?
In General No, The party that caused the accident is liable. However, If You were driving a company provided vehicle a the time of the accident, then the company may have some secondary financial liability depending on the circumstances of the accident.
The maker of the golf ball the maker of the club and you.
The additional driver
Yes.
the person that owns the car
Who is the owner of the car your adult daughter was driving, you or her? If you, you can both be liable. Her as the driver, and you as the owner of the vehicle
Typically the person that rear-ends the car is the driver sited for the accident. Usually, for following too closely. It is very rare that the front driver is sited and/or held liable for the accident.