How to use the Shipped Date, instead of Receipt date for dropship orders.

For dropship lines the PO will be created.  Then when is doing the receiving they can enter 2 dates Receipt Date, Shipped Date.  Receipt date is the date they are doing the receipt.  Shipped Date is the date when the vendor shipped the product to the customer.  After the receiving is done the SO line will be logically shipped and closed.  But in SO line the Actual ship date is coming from Receipt Date instead of Shipped Date.  Is there any profile or system parameter to change this behavior.

This is causing wrong data capture on SO line because the vendor ships the product to customer, but inform to our buyer somtimes after 2-5 days.