Auto Fetch Custom Field From supplier_items


I’m trying to add data from a custom field created within the supplier_items table of the Items doctype. I’ve successfully created the field and added data to the field within the Items doctype, however, I just can’t seem to pull it in to Item Price doctype.

I have tried using data, read only and link with various fetch from terms. What am I doing wrong?

Custom field is ‘Supplier Part No’. I have tried ‘supplier_items.supplier_part_no’, ‘item.supplier_items.supplier_part_no’ and just ‘supplier_part_no’.

Any suggestions are appreciated. Thanks