as an other person from the philly burbs, i felt compelled to answer......
however, i am not sure exactly what you mean. i have some questions and some long answers.
how do you plan to purchase the
DDP? do you want to add it to your tickets once you are onsite or are you buying the plan as part of a room/ticket/dining package that you will be purchaseing online or over the phone?
i know that any online or over the phone purchases would have to have some sort of down payment, not necessarily a credit card, they give you some sort of grace period where if they don't have a payment (either mailed or over the phone) by then to hold your ressie, it will get cancelled.
not sure if they would accept disney dollars in the mail as payment for one's vacation. i know they will take them at the resorts as payment on your package when you check in. (if you have the kind of reservation where you can pay when you arrive as opposed to having to be paid in full before arrival.)
your best bet, instead of gifting her with disney dollars, give the disney gift cards. you can get them in the
disney store, the same place where you can get disney dollars. you can get them in any increment that you want and i believe that you can add funds to that card later. (get the card, with a certain amount on it now for a gift and if you or someone else wanted to contribute later to this person's vacation account, they could add to that card.) i believe those cards can be taken online with CRO as a credit card for payment on a reservation or ticket media.