Modify Crystal Re;ort

I have an existing report created in Crystal Reports which reports on various cost codes, 01 - 99. The report lists each item for each cost code and then sums each cost code as well as provides a grand total. I need, added to the existing report, a subtotal column that includes all cost codes between 01 - 16 and another that totals all cost codes 17 - 99. These 2 new columns should come before the Grand Total line. The existing report will be provided. Please note there will be no connection to the database.