You must of course use a different tax identification number. If she has her own tax ID, there should be no problem in setting up an account.
Of course there is also no problem in your publishing her books on your account, if she's willing to trust you as an accountant! You can put any name as Author of a book, within reason. (That is, if your author name and real name is Stephen King, you'd better have a birth certificate to prove it....)
(Don't trust KDP to publish a print edition. Don't trust CreateSpace to publish an ebook.)