AS code-share flight (but only for miles)?
 

I realize this will soon to be a moot issue, but...

Was looking for a pair of tickets SEA-DCA, one for myself that I'm booking through corporate and a miles ticket for my wife. Noticed that when I select price in Miles, AS codeshares appear (which are direct flights - there are no directs on DL metal to WAS or BWI). When I switch back to showing prices in dollars, only Delta metal flights show up. Is there a reason for this? As is, my wife is taking a direct flight, Because She Can, and I'm catching up with her a couple hours later because Corp.

I think the simple answer is that code-sharing for revenue and code-sharing for award redemption are two different agreements ... the former disappeared a couple years ago, but the latter will last until the DL/AS partnership formally dissolves at the end of April

Award tickets are booked as the operating carrier flight number. Code-shares are booked via the codeshare flight unless the fare allows booking on the operating carrier flight number. It's very rare for one carrier to have a fare nowadays that will allow you to book using another carriers flight number. This is the whole point of codeshares.

DL/AS have ended the codeshares already. They continue to allow booking award flights on each other though for a short period.