Sales Order Relationship Subtab (CSV Import / API?)

Hi, this is my first post here so be please kind and I look forward to all suggestions here that can make my experience better here.

So I have am working on a new integration between Salesforce and Netsuite and one of the requirements is to populate the Sales Order Relationships subtab with the matching Contact record from the Salesforce Opportunity Contact Roles.

To begin learning the correct tables and formats, I have begun to use the CSV Import function to populate data which has been a great exercise in determining the API requirements but I have not been able to find the correct import type to populate this data. I have not been able to find these data points in the schema browser as I would guess the naming convention itself may not be related to Sales Orders.