<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Altaflyer:
Also, in the miles example above I believe that the NW flight miles would credit as NW partner miles and not AS miles and would thus not count toward the lower AS mileage requirement.</font>
Yep.
However the counter example would be a NW or AA code share operated by Alaska or Horizon. In that case the miles for that flight would count towards the lower AS/QX mileage requirement.