Can you break up a payment between two cards

This may help.

Using more than one payment method

You can also combine payment methods to pay for your purchase. Choose from the following combinations of credit cards and gift cards:

• Credit card(s) - up to two
• Apple Gift Card(s) - up to eight
• Apple Gift Card(s) - up to eight + one credit card
• Apple Gift Card(s) - up to eight + Apple Account Balance
• Apple Gift Card(s) - up to eight + Apple Account Balance + one credit card
• Apple Gift Card(s) - up to eight + Apple Pay
• Apple Gift Card(s) - up to eight + Apple Account Balance + Apple Pay
• Apple Account Balance + one credit card
• Apple Account Balance + Apple Pay

Payment, Financing, Refunds and VAT - Shopping Help - Apple

Hi there,

I understand you want to pay something with two different cards.

That previous answer may help you:

‘You cannot split an order across multiple cards online. However in an Apple Retail Store, payment can be made through multiple methods including two different cards in Apple Pay although they will have to be presented separately.’

Actually online -

You can use one card to buy an apple gift card to the amount you need (from card one). Then apply that at checkout and pay the remainder on your second card.

That way you can use two cards to spread the payment.