How to perform Ship Confirm Transactions for partial Line Quantities using Rest API

We have a requirement to process only Ship Confirm since the Pick Release data goes to a 3rd Party application. So we tried using the REST API for achieving this solution. We tried using "Shipment Line Transaction Request - /fscmRestApi/resources/11.13.18.05/shipmentLineTransactionRequests" for splitting the Shipment Lines so that Partially processed quantity will move to "Awaiting Billing" with a Delivery Numer and the remaining quantities will be in "Awaiting Shipping" status for the next Delivery to pick.

We tested a sample Sales Order with 5 Quantity and used the above mentioned REST to process only 2 Quantities. The REST API's functionality is to insert the data into WSH_DEL_DETAILS_INTERFACE, which it did. But there were junk and default values Inserted in the Interface Table. Below is the Request and Response Body used.