Went back in February, had my Dining Plan as part of my account. When I booked SoA, it asked if I wanted to pay or use Dining Plan and guarantee with a credit card, or pay up front. I chose to use the Dining Plan. I did have to put in my credit card details.
However, it then proceeded to bill my credit card for the full amount!
Rather than cancel and risk losing the reservation, I left it like that. When we went to the dinner, I mentioned it to the person we checked in with, she had no idea. I mentioned it to our server (Tom) and he took our KTTW and came back after a little bit with a printed receipt confirming the refund was processed to the credit card. He was also very attentive, friendly and funny.
Bottom line is you're supposed to be able to book it on using your
DDP, but it didn't work. I'd recommend calling and talking to someone rather than trying the self service that I did. But even if they do charge it, they can fix it.