How to have many Form Letter templates and use 1 concurrent program/XML output

 I have an XMLP/R12-BIPublisher requirement to create many Form Letters.  The users would like to be able to have parameters that would be used as content in the Form Letters.  The Forms Letters could be built using same concurrent program/XML output/SQL Query, other than they would have different parameters to add content to the Form Letters.  Is there a way to have 1 concurrent program/XML output with many templates, where the templates have different content parameter (not parameters for filtering data).?