Hi Percival, 

Only Pete and his son are able to use Pete's PIP.  Joe, the son's friend, cannot use Pete's PIP to pay for his injuries.  

Pete - $8000 X 80% = $6400 and Jim (Pete's son) - $5000 X 80% = $4000

$6400 + $4000 = $10,400

I hope this helps.  Please let me know if you have other questions.

Jan