More FMC/PFD strangeness

This was the end of my flight into KSEA (from KEWR) note that the RX-16R entry is not listed as a wayopoint on the FMC, but it does show on the ND- as a point off of a previous waypoint, where I entered the arrival info.I've found that I have repeated issues in entering arrivals- If I enter a STAR and no runway, then return to enter the runway while in flight, my star will be dropped and I may or may not get the RX data. If I change the runway, but do not reenter the STAR, the STAR will be dropped, but I will get the RX data.This may be the way the logic is designed, but in every other Sim Boeing that I've used, I can change one (Star or runway) independant of one another with them remaining in the active (or Mod) plan. Makes it easier when you have a runway change and don't want to redo all of your speed/alt constraints on the Star.Timhttp://forums.avsim.com/user_files/22215.jpg