Updating an Intercompany sales order which is paired with an intercompany purchase order will throw the following error:
You cannot change the GL impact for intercompany inventory transfer lines
As of NetSuite standards, we couldn’t make a GL-impact change on the Intercompany Sales Order that was created from an Intercompany Purchase Order.
Any modification made to these orders will cause an accounting discrepancy between the purchasing and the sales parties, so it is designed in this way to keep the GL Impact consistent throughout the process.
Users are prevented from making GL-impacting changes after the Intercompany Sales Order and Intercompany Purchase Orderare linked as a pair. So the better solution is to remake these orders with the correct data.