Customize Form - Parent Doc Linked Data

Wanting to know if there is another way (without creating custom script) to pass existing data from a parent doc to related doc, example being from Delivery Note Item to Packing Slip Item, where the field is not a custom field.

I know you can pass custom field data over in the example above per below, however when trying to link standard data fields like ‘warehouse’ it will not work. To get around this, I hide the existing ‘warehouse’ field and added another custom warehouse field. The issue with this is the warehouse field in Delivery Note Item has hard coded validation etc against it when populated from the Sales Order Item, so I cannot do this.

What are the thoughts of having a tick box or ‘flag’ which can be set on any data field to indicate it to be passed?