Pricing Conditions - Renumbering the Steps

I recently had to completely renumber the steps on 2 pricing conditions that have been around since about 1997. the reason for the renumbering was that the originals were created in step increments of 1 (1,2,3 etc.) rather than 10's so it left no room for new steps in most cases. These specific pricing conditions are generally updated once a year and the update includes 2 to 6 new steps that have to be fit into the scheme.

In the above case I copied the old version (i.e. ZZRTLR to ZZRTL1), completely remodeled it, deleted the old (ZZRTLR) and renamed the copy (ZZRTL1) as the new version (ZZRTLR).

The new version works just fine for all current year requirements but we do have to reprint last year's invoices from time to time and that results in an invoice that no longer makes sense. In some cases it will insert values in the wrong line, miss lines, include values in the 'Subtotal before Tax' that shouldn't appear, etc. The reason for that is that the output looks to step # to find the value, if that step has been renamed then it will insert the value where it believes it belongs - or not. Unfortunately almost every step has either been renamed, renumbered or ceases to exist.

Question: is there a way of getting the output to appear on the appropriate line? What are my options?