Two Different Flights, Same Flight Number -- Impact to Traveler?

My regular route includes two different flights, with an hour and a half connection. They have always had different flight numbers in the past. The flight numbers are changing in the future and now these two flights will have the same flight number, but everything else about the two flights except the fact they have the same flight numbers will still be the same.

I have three questions:

1) The NW website won't let me select a different seat for each flight anymore once the flight numbers are the same. That greatly reduces the number of seats to pick from since the seats I have available to select from have to be available on both flights. It leaves me with really crappy seats to pick from. Is there any way around this phenomenon?

2) Is it possible for an upgrade to clear for one of these flights and not the other or is it a one shot deal, all or nothing, once the flight numbers are the same? My experience with these same two flights with different flight numbers is that one never clears and the other always clears. I am worried that the one that always clears won't clear anymore if it is an all or nothing situation.

3) Is it true that the miles and segments earned will decrease on these flights even though nothing has changed but the flight numbers?

answers:

1.)No That is considered a direct flight so the seats you have from the intial origin will be to the final destination.


2.) See above. The EAU will consider it one flight and will upgrade accordingly. "most likely" if there are first class seats on the second leg an attentive gate agent or flight attendant will invite you to move forward.

3.) You will earn miles for the direct flight but not the segements. You can send a TTU and call but they still will count it as one segment which is irritating but unavoidable.

Most likely it is the same plane continuing on but probably either different pilots or flight attendants.