You can add some custom fields in add/edit purchase & view purchase.

To enable custom fields:

  1. Go to settings -> Business settings -> Label for purchase custom fields:
  2. Provide a label for the fields you need, fields will automatically get enabled once the label is added.
  3. Check “Is required” checkbox to make the field as required in add/edit purchase.

Content retrieved from: https://ultimatefosters.com/docs/ultimatepos/purchases/purchase-custom-fields/.