I have 14553 points with NW that I have had for awhile. Can I purchase a ticket with any other FF program where I already have points with these miles?

Maybe I could find one that has a 15000 pt requirement only. Does NW allow this or how would it work?

Do I have to use a "middle man" and lose on the points or can I get around this at all or do I just have to wait and try and rack up the balance to make 25,000. Hate to see these just sitting here when I can really use them
Thanks