I hate to offer a morbid suggestion, but - why not allow your father to keep the miles, and use them to purchase tickets for you and your family. When your father passes away, Delta will allow you to transfer the miles to his heir (with NO fees). I went through this process with my father's SkyMiles account when he died. Basically, you just send Delta a copy of the death certificate, the will, and the SkyMiles account numbers. I know, it's one more thing to do during what is already a trying time, but Delta makes the process as easy as possible.