Credit Card Split Shipment Issue

We are facing an issue as the Credit card Authorization at Receipt creation, is creating problems for Split shipment issue.

1. Order is placed for header amount 1000$

2. Customer Credit Card Limit is 1000$. So first Authorization for 1000$ is successful in OM

3. Order line is split into 2 lines. first line has 400$ and 2nd line has 600$

4. Order line with amount 400$ is shipped. Invoice and Receipts are created for the 400$ line. Receipt creation program captured 400$ from original 1000$ authorization. Remittance program is not yet submitted

5. Order line with amount 600$ is shipped on the same day within an hour. Invoice and Receipts are created for 600$ line. Receipt creation program is not using the original authorization of 1000$ to capture 600$. Receipt creation program is creating a new authorization of 600$ on the credit card. Since the Credit card limit is 1000$ on the Credit card and there is already a 1000$ authorization, 2nd receipt authorization is failing.