Book Delta flights using Korean Airline miles. If you can find space on Delta for 45,000 miles RT, you should be able to book it with 25,000 Korean miles transferred from UR. You'd want to confirm that KE sees the same flights available before transferring any points. You will probably also need to go through their process of proving you are family members so you can book flights for the rest of your family using your miles.
I've done this twice now, and it saves a ton of points. Looks like there is plenty of space if you are willing to go mid August or so.