Ssrs 2008 obtain counts using outside groups

SSAS and SSRS
1

In an ssrs 2008 report, I would like to add the following to an existing report that contains data:

  1. Get a final total of all the control groups that are by school number,
  2. The columns each group of data contains counts by school number.
  3. The counts are not unique vy control groups. There is alot of redundant data.

Due to the above, I would like to know how to:

  1. Add counts for outside groups, and
  2. How use distinct values by school number.
2
  1. Add new data sources to your report, if the data is from a new source other than the data source that already exists on the report.
  2. add new data sets to report
  3. insert visualization component (matrix, graph or whatever) that point to new data set from #2
3

The data is already obtained from a data source that the report uses. Since this is occuring,I cannot use a nhew dataset correct? If not, I have only been able to make the main dataset be used for the report. The other data sets I have used are only for parameter logic.

In my case, can you tell me how I can setup an outside group using an existing dataset and/or make the report use a different dataset that is actually the original dataset?