I'm not sure I understand what you are after Jon but consider the following:
At the very start of running a report crystal checks whether the report (or any subreport) contains parameters and if they do, it must prompt you for them before it even queries the database.
So, parameters are "fixed values" as far as the report is concerned.
Therefore you cannot get a prompt to appear part way through a report.
Does this help?
Steve Phillips, Crystal Reports Trainer & Consultant