macro substitution on report

[Scott K.]

I have a report that is built over a cube.  The report has several charts on it.  I also have a 2 value prompts where the user can select the "To Date" period and the "% Change".  I would like to be able to combine these into 1 prompt so the user has to select only 1 item and not 2.  I tried putting an if - then - else into a data item, but the report through an error because it referenced more than 1 time element.  As an example, I tried putting [Current MTD],[Current MTD +/- LY %] into the "use" value of the prompt and used the substring and position function to split it out so field1 would use [Current MTD] and field 2 would use [Current MTD +/- LY %], but could not get it to work.  The report has several relative time period fields on it, and I use another data item with the macro substitution to use the "report" data item the user selects.

Currently each field on the report has the following syntax:

#prompt('p_time','token')

Is it possible to parse a value from a prompt and have it treated as if the user selected from 2 different prompts?