Go into Settings > FaceTime on her iPad, turn it ON and set up the email address you want her to receive at. If you've already set up her email account under Settings > Mail, Contacts, Calendars > Add Account, you should have at least one entry already. Make sure the Caller ID matches to avoid caller confusion.
You can also visit Settings > General > Sounds and choose a Ringtone. This is what she will hear for incoming calls.