The View/Place Order function is useful for ordering additional copies of a title that is already in the catalogue.
Click Other Actions → View/Place Orders
Click Add To Selection List
Type the beginning of your selection list name into the field and then select it from the drop down that appears.
Click Apply.
See Chapter 7, Adding Line Items to Selection Lists for ways to add additional line items.
OR
See Chapter 12, Working with Line Items for information on updating your line items.
OR
See the section on creating purchase orders via a selection list.