Invoice formatting options - Sort-by fields

Hi,

    Can we add the field "Product_group" to the prompt values available in Sort by fields page - "sort-by" prompt values for a Sort by ID,also how to add a new sort by ID and add and assign the new sort-by fields. how to add a field to the list of prompt values.Currently this prompt values has "PRODUCT_ID" and "PRODUCT_GRP_SETID" which is not needed for me and i need to add now the below list of fields to the prompt values.

Main Menu>Set Up Financials/Supply Chain>Product Related>Billing>Setup Invoice Options>Sort-by Fields