Current functionality of Auto batch determinization in Outbound processing doesn’t allow any manual changes of batches. Please share some work around:
Could you please check if the following blog helps you - https://blogs.sap.com/2021/05/06/batch-determination-setup-scenario-in-s-4hana-cloud/
The section of the blog "Activate Automatic Batch Determination for Sales Order / Delivery Item Categories" should help here. It explains how to setup which item categories have a batch automatically selected on the sales order, and which on the delivery.
However, If you want the batch to be first determined on the sales order, that selection will be prepopulated on the delivery, and as you noted, it is not changeable. This is intentional for a number of reasons such as batches being sold and determined based on a customer's requirements, as well as pricing based on a batch's characteristics.
So if there is a requirement of batches to be determined on delivery not in sales order level, and this is why you switch on the automatic termination in OBD, but warehouse will not be able to change it afterwards. For some reason, that is possible only in sales order level and warehouse doesn't want sales team to do that. Batch change must be done in warehouse (OBD), not by sales team (in SO).