Apology if this was discussed beforehand as I could not find the right answer.
I was wondering how to change LH codeshared flight number to original NH flight number to apply the PP for upgrade. I understand if the flight is UA code-shared, one could call the UA to change the flight number to original carrier's flight number (back to either NH or LH flight number).
Can you do the same for the LH? If I book a flight on LH and if the segment (e.g.; HND-FRA) is booked with LH code-shared flight number, can I call LH to change it back to the original NH flight number so that I could apply PP?