This functionality is new as of version 4.0.
To Add a Product not on the Purchase Order:
Navigate to the ‘Purchase Order Details’ screen → ‘Delivery’ tab.
Click the ‘Add Product Not On Purchase Order’ icon next to the blank 'Product' drop-down field.
The icon will change to the ‘+’ (plus) icon.
Select a Product.
Enter the 'Line' and 'Seq'; OR,
Enter the 'Line' and/or 'Seq' to filter the 'Description' drop-down list.
Enter the Product Name, Alternate ID, or Synonym, in the 'Description' drop-down list.
Click on the '+' (Plus) icon to finish.