Sorry if my comment was OT, but it was in response to someone else's statement in the thread.

100% in agreement with you there. DL.com should be able to handle input of non-DL FF #s at the time of ticket purchase, no question. However, I don't think that's what this thread is about--it's about NW FF#s disappearing from DL tickets in favor of DL FF#s.

There seems to be a sentiment among many that DL deliberately removes NW FF#s from people's records and inserts a DL#. I don't believe that to be the case. In my experience, it's a screwup. As NOLAnwGOLD points out, if there's already a DL FF# in your record, many agents will simply add your NW# rather than deleting your DL# then entering your NW#. This is likely to cause miles to go to DL rather than NW. Is that wrong? Yes. Should the agents be trained better? Yes. Is it a nefarious plot on the part of DL to 'screw with' peoples FF accounts? I think not, but you're free to disagree.

I have has something similar happen but with CO and NW. I was traveling with a friend who was using his NW FF # .I was using my CO#. Due to an agent screw up, his NW # got associated with my record mid- journey. The NW number replaced my CO#. I noticed this when our boarding passes printed on the first leg of a multi leg return. They were able to re-print the boarding pass for the future legs but claimed to be unable to correct the already flown legs that were associated with my friends' number. I was told that the agent could not correct it since segments had already flown. I tried to get this corrected at every point during the multi leg journey and even at a CO office and all claimed they could not correct it and I would have to mail in the boarding pass for correction. I know CO is not DL so what you have to do may be different but the agents along the way seemed to be pretty sure that they could not ( or were unwilling) to make the correction once the segment was flown.

Yes. (There have also been threads before about people who put their DL# in when booking online in hopes of getting a bonus for doing that, then go through huge amounts of trouble on the phone to get it switched over to their NW# for the actual flight.)

Agreed.

Sounds like we're mostly in agreement.^ I never meant to imply that DL shouldn't allow adding other FF#s at the time of purchase or train their agents better to avoid problems. My real gripe was that several of the posts here seemed to be implying that DL deliberately switches people's FF#s, which I just don't think is the case.

While DL should resolve the issues on their end, it's relatively easy (in my experience) to have problem-free crediting of DL flights to WP. Based on my personal experience and the numerous posts I've read, I suggest the following actions:

1. Make sure your NW FF# is the only one ever associated with the ticket. Even if you don't remember your DL FF#, don't "log in" to DL.com--it is probably saved in a browser cookie, and logging in will enter you DL FF#. If a phone rep asks for a DL#, just say you don't have one. If you buy a ticket through a third party (including online sites) make sure your DL# doesn't get entered--in many cases, booking a ticket on airline X will result in airline X's FF# being entered into your record. Cookies and server-hosted records at work again.

2. Until DL gets their act together to allow entry of other FF#s on their website when buying a ticket, e-mail DL to have the number input. A number of posts show that this is far quicker and easier than calling DL's phone line.

3. Make sure your NW# is on your DL BP before boarding--if you follow steps 1 and 2, it shouldn't be a problem. If it doesn't work out that way, then make sure it does before you board. Don't buy a GA saying that your NW# is in the record and miles will be credited to NW if a DL# is on the BP--the miles will really go to DL if the DL# is on the BP. Ask the agent to fully delete all FF# info and re-enter your NW#.

I have had problems with DL and my WP# in the past. In my case, the number that they had on record for me was just plain wrong (numbers were switched around). When I brought this up at the gate, they told me that I must be mistaken, because "their system checks for that sort of thing, and it wouldn't have allowed the connection of an incorrect number to my name." When I showed them both my NWA WP visa card, as well as my NWA WP card with the right number on it, they still maintained that I must be wrong...
Anyway, I finally got the 3rd GA that I asked to change it (even though the other two claimed that it was impossible).

Also, I'm not sure that I want all of DL's elites getting upgrades on NW. I don't fly DL enough to take advantage of that benefit...

I purchased my ticket through a travel agent and did not go through any websites. Before my trip, the entire ITN was on NWA.com. I got my boarding passes for the first two legs at the NW counter and both had my FF#. I was upgraded on the first leg which was on NW metal. I was not upgraded on the 2nd leg which was on Delta.

Definitely good advice. I've got a simplified version: I have a NW FF#, and no DL FF#. So if I'm on DL, or any other NW partner or SkyTeam member, there's one and only one number they can possibly use.

Yup & Yup. It's what I do.

As an added note: A Delta (metal) flight (6am departure)of mine got canceled. They wanted to rebook me on Delta metal later that day(3pm), to SFO (from east coast). I insisted on a codeshare CO metal flight that departed aprox. same early time as original flt (as it was only a 2 day trip and losing a day was not an option), had to have a Supervisor do something & OK it after the agent said it was not an option & could not do anything.

Anyone have the email addy to use for this? Delta's version of TTU won't deal with reservations.

hmm..I use their TTU to make this change all the time

I just did this, and the email reply says they added it, but I'm unable to access the preferred seating. Is this a problem with DL not automatically recognizing NW FO status, and should I have specifically mentioned that I was Elite, or ... ?

I have mistakenly ended up with my little-used SkyMiles number on a DL ticket instead of my WP number. The miles went to my DL account. It's the only time I have had to get the WP Service Center involved, but they did fix it for me. The only way I can think that this happened is that I had "Remember Me" checked on the DL website. When I pulled in my reservation by Conf #, the WP FF# magically got changed to the DL SkyMiles #. If you ever look at your DL itinerary on the DL website, make sure you are not signed in and make sure you pull up the reservation by Credit Card # or Confirmation #. In other words, just pretend you never had a SkyMiles #.

Someone also said that if you buy a gate upgrade on DL metal, they make you enter your SkyMiles number. This is not true in my experience. I flew on DL last year. I was so exhausted from SkyWest's butchering of my inbound flight into SLC that I bought the upgrade at the gate on the connecting mainline DL flight. I had my Continental OnePass number in the reservation, and there was no problem. The miles showed up in my OP account. I would expect the same would have happened if I had had my WP number in the DL reservation instead.

It does help to state something to the effect of 'based on my ST Elite status, I'd like to be switched from my current seat to seat 8C'. Is your NW status recent? It could take a week after NW recognizes your a new status level for the status to be communicated to DL. Other than having recently earned Silver, DL should not have a problem recognizing the fact that you have Elite status on NW.