Add payment method to my daughters ipad

See >>> Change, add, or remove Apple ID payment methods - Apple Support

If you only have a single Credit Card set-up for your AppleID account, you will need to add a new Credit Card to your AppleID account - after which you will be able to delete the old card details. 

It is often a good idea to have two (or more) payment cards associated with your account - as, in case there is a problem with your primary card, a charge can be made to the second card without risk of impacting ongoing access to your AppleID account or associated services and subscriptions. With multiple Credit Cards, you can choose the sequence in which card payments are made.

You may find these support pages to be helpful:

If you need to change or update your Apple ID payment method - Apple Support

Add a payment method to your Apple ID - Apple Support

Remove a payment method from your Apple ID - Apple Support

Payment methods that you can use with your Apple ID - Apple Support

If you were using Family Sharing it should update automatically.

If you were not using Family Sharing see this article about updating payment methods on various platforms (iPhone, Mac, etc.): If you need to change or update your Apple ID payment method - Apple Support

"If you change your address, the credit or debit card information that you use with your Apple ID might be automatically updated by your financial institution, and you don't need to take action. But if there's an issue [such as you having a subscription or being a Family Sharing Organizer], add a new card first, then remove the old card."

Here is how you update your payment method on an iPhone or iPad:

1. Open the Settings app.

2. Tap your name.

3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.

4. Tap Add Payment Method, enter the new payment method, then tap Done.

5. Tap Edit.

6. Tap the red delete button next to the old payment method, then tap Delete.