Crystal Reports Group Sort based on formula

Message

     Hello folks,

I have created a crystal report that pulls from a SQL stored procedure.   The basis of the report allows them to do a count of of patients by location(zip code).  

The report prompts the user for 5 different group parameter fields I created (Group1, Group2, etc) allowing them to control how the report groups the information.   They also have the ability to use a group of "None" which will then blank that group out entirely when the report is runs.    The report is set to show the total count of patients by zip code based on the last Group parameter field they selected an actual field to group by.   Whatever the last group by field is that isn't set to "None", the report automatically assigns one additional group by field called "Zip Code" above it and this is where it shows the totals by zip code.

Here's the issue I'm stumped on.   I want it to have it show the zip codes in order from highest count to lowest count.   I know I can do this by using the "Group Sort Expert" but it makes me choose the group I want to do this on which could change each time the user runs the report and changes the way they want it grouped.    

For example, the first time the user runs the report they could choose the following groups:

Group1: Year
Group2: Month
Group3: Type

The report will then automatically add the zip code group to Group4 on the report suppressing the rest of the groups.  In this instance I would go into "Group Sort Expert" and select "Group4" as where to sort "All" by the count.    However, the next time they run the report they may just want:

Group1: Year
Group2: Month

In this scenario the zip code group now falls into "Group3" and my Group Sort Expert" doesn't work.   If I tell it to Sort "All" on every group it start rearranges my other groups which I want to show in order.   

So in essance, I want to try to throw some type of formula in that says 

If Group1 = "Zip Code" then Group Sort "All" by count ELSE
If Group2 = "Zip Code" then Group Sort "All" by count,
.
.
.

There doesn't seem to be a way to create formulas for the group sort expert and I was wondering if anyone found a way around this.

Sorry if the post was long winded.  It's a very complex report and I wanted to try to make sure my dilemma was understood.

Thank you in advance,
Chad