Thanks for responding, but unfortunately it doesn't address my question. I appreciate the attempt though.
Context: I have two rooms reserved, paid for (including the dining plan), and managed by me. Except that Disney can't seem to separate the concept of "guest responsible for a reservation" from "guest present in a room", nor will they allow me to be listed as the lead guest on two rooms. So one of the rooms is officially under my mother's control, but she knows nothing about anything Disney. And that's the room with the dining plan. I could have mom call to book the reservation, but she wouldn't have a clue what she was asking for. I could call and "be her" (it wouldn't be the first time), but I'd need to get her credit card information for that, since they'll still want a credit card guarantee, and probably wouldn't look kindly on "mom" offering up my credit card. And for whatever reason, the dining plan is not showing up as a payment option when I try to book through my mother's
MDE account (which I created). I gather from other threads that this is a common problem. Could be because I added the dining plan as a DVC add-on instead of booking as part of a package.
If nobody has direct experience with this sort of situation, I'll just go ahead and book the reservation and sort it out upon arrival. In the worst case, we either cancel the reservation and just don't go, or cancel and rebook immediately with the dining credits (although from what I understand, that's likely to leave us with "worse" seats).