A related but different question to the one earlier in the thread.

As brief background, I got a good deal on a SAW-TLV flight operated by AnadoluJet (TK out of IST on the same day was far more expensive). I just had some good luck in that due to a change of time to my original flight I was able to change flights for no cost, so opted for a flight on TK out of IST which suits my timetable. It’s a more preferable option for me as it means both lounge access and a free checked bag (NZ*G).

I was hoping with the change of operating airline that I’d be able to credit the flight to NZ (who have different rules for some Anadolu operated flights). It turns out that’s a moot point anyway as the original booking class was U, which doesn’t earn anything to NZ regardless of it’s a TK or Anadolu operated flight.

Rather than earning no points anywhere the only option would be to credit it to TK’s M&S.

My NZ ff number is still attached to the booking and my intention is to leave it there for now to obtain lounge access and free checked bag. I’m aware that in some other airlines, by changing ff numbers after checking in, their systems will try and charge you for baggage if the new ff number doesn’t allow for a free bag.

So my question is, is there any risk in me changing my ff number (with the lounge staff?) from my NZ number to my TK number of them asking me to cough up for a checked bag? Or would they simply not allow to change it once I’m checked in and have entered the lounge (which sometimes happens when flying on NZ)?

Thanks in advance.