Using both GiftCard Payment and Credit Card Payment in Web Payments SDK for Split transaction

Hello, I am trying to use square web payment sdk to take the payment using a gift card and if there is still any outstanding, need to use credit card sdk. I do not get the outstanding amount after using the gift card sdk. As an example my order value is $120, I have a gift card for $50. I used the gift card sdk to make a partial payment of $50 and I do not get the outstanding amount to charge to credit card. I am not able to get the gift card number to retrieve the balance and determine the outstanding amount. Is there a way to cover this split transaction using the Giftcard and Credit card sdks by square?