I used to very easily be able to book NW domestic segments with the help from a tool such as KVS to have the right dates and flights available for the call with FB but have found it impossible under DL. Just check out their own forum where they cannot find availability at all, let alone the low level awards which show up for FB.
You are better off just assuming that AFKL have NO US PARTNER and just find the cheapest paid ticket out there you can find, or switch to *A for most of your flying as a good deal of this forum has done during the last year. With the formation of UNITED including CONTINENTAL, *A will be an even more attractive alternative. DL is not really worth wasting your time on.