how do I add my wife's ipad to my itunes account?

I think my wife has her own itunes account, but she never has actually accessed itunes or set up a credit card on file. Is there a way to add her ipad to my account so I can more easily put the tv shows that I have already purchased onto her ipad? When I attach her ipad and click on her ipad, I do not have access to the same tv shows that I do when I attach my own ipad. Thank you.