I didn't follow all your posts back and forth about code shares.... but your 4984.00$ fare to NAP over Christmas is really $3045.00 booking AC and LH apart, everything in P class, all seg available.
...
1900$ difference is not worth the AQM on FRA-NAP-MUC
That's the reason I don't book codeshares, even if they earn me AQD next year. There are just so many disadvantages with codeshares that make them unattractive: no online check-in, no seat selection, no upgrades.
My flying pattern next year, even without booking codeshares, will clear $20K AQD no problems, so I will not put myself in a disadvantaged position.