DDE recently changed its rules to provide greater assurance the DDE holders are eligible according to the rules. You're best bet is to be an AP holder yourself, and then apply for the DDE.
If she purchases a DDE card, the card will be in her name so I guess you could do it but you may be taking a chance if they ask for ID as they do that on occasion (not lately but I've been asked for it in the past).
And keep in mind, you'd also have to "fib" making your ADR's (and put them under her name) as the host/hostess fills out a ticket with your name and the ticket is then given to the server when you are seated.
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