As to the original accident, at least down here the car that hits from behind is at fault.
Dad was involved in one, when a young guy fitted a V-8 to his Kingswood and kept the 4 wheel drums.
Lady slowed suddenly to turn, causing a heavy braking cascade for 3 cars. All were slowing when kid in V-8 couldn't stop, and drove into Dad's car, forcing him into the one in front and so-on.
The process involved the car in front attacking their rear ender's insurance. That got rolled into the third car's insurance, then those three cases got rolled into Dad's insurance.
Should have rolled into the kid's insurance, but he didn't have any. So it stopped at Dad's policy.
Insurance company was supposed to sue the kid but apparently cut their losses, as all of the witnesses were never called.