Originally Posted by
FlyingHoustonian
would changing the tickets from 016 to LH stock change PQP and earnings on UA?

You would have to cancel and rebook - there's no way to change ticket stock. If the itinerary were to be rebooked on LH stock with LH (or any other non-UA) metal, you would use the "non-016" tables for determing accrual - they're based purely on distance and not on fare.