Apple TV Subscription

In 2019 I purchased a iphone 11 and received a free year of Apple TV. This year (2020) I purchased an iphone 12 and an ipad for my wife for Christmas. When we try to use Apple tv on her devices it keeps trying to set up a new account. How can I extend my initial free year to include the free years it is now offering. I don't want two accounts in the same household.

Thank you,