Hi,

Seems you are looking to make the source field always visible ? If so, you can inherit the corresponding view from the code or from the ui and make it possible.

In the above image you can see there is invisible attribute set, so as per this condition, the field will be invisible if there is no value inside this field. Normally the value to this field is get set based on the auto generation of the PO from the SO, MRP based on the configuration in the database.

To make it visible you just to need to remove the attrs="{'invisible': [('origin','=',False)]}" from the field, which you can do by inheriting or directly editing the view from the UI in debug mode. The first one is the suggested method.

Reference: How To Change Existing Field Attributes From User Interface in Odoo

Thanks