Reporting Services :: Using Parameters To Filter A Report?

I have a report I'm working on that provides a census of members. These members have certain properties;

Load date,Report Type,Clinic,Care Manager,PCP Name.

The census is from an outside group and what I do is massage it for our internal databases and reports to our care managers.

The report starts out by returning only those entries that were received in the last report from the outside vendor and I filter each of the parameters by using a WITH statement and an INNER JOIN, as follows;

WITH Date_of_Most_Recent_Census AS
(
SELECT
MAX(Load_Date) AS [CurDate]
FROM
Census_Rpt_Final
)

[Code] ...

The default is for all parameters to start out with all possible values for the current load date. But, I need to be able to filter the available - and default  - values for each parameter based upon the selection of the other parameters.

So, the Load Date is built in by use of the CTE that is a part of all the parameters. But, I need the report to allow the end user to select from each of the others, but limiting what is avaliable for selection based upon the settings of the other parameters.

For example, the second parameter is the Report Type. It can be either "Hospital," or "SNF." But, not all Clinics, Care Managers or PCPs may have an entry in both types. So, if the user selects, say, "Hospital," all the parameters would alter their available and default values such that they only include options where the census shows they are a "Hospital" entry.But, not all Clinics in the most recent census may have both report types. So, if the end user selects a particular clinic, it would also recalculate the available and default values for Report Type, as well as those beneath it on the list. And, likewise for the remainder of the parameters.

My initial thought was to add WHERE statements to the datasets controlling each parameter, but SSRS keeps asking me to define the parameters when I click out of the dataset's properties. Now, I know that SSRS is a single pass process - and, I'll cross the bridge on adjusting parameters defined earlier in the list when I come to it - but I thought that parameters lower in the list would update, since they'd have their values defined.For instance, the Clinic parameter is after Report Type, so the code I used to set up Clinic was;

WITH Date_of_Most_Recent_Census AS
(
SELECT
MAX(Load_Date) AS [CurDate]
FROM
Census_Rpt_Final
)
SELECT DISTINCT

[code]....

But, this asks me to define @ReportType, even though it precedes Clinic on the parameter list.