Since this is an Enterprise Forum I'll give you the method I would use for this sort of reporting using enterprise.
I would create the first report, which would output a file to a specific location, in the Enterprise report properties output tab.
Then create an event in Enterprise which would be triggered by the creation of this file.
The report you wish to create based upon the file you created with the first report would be scheduled to run every x mins with a dependancy upon the event created.
This second report should produce the results you wanted.
The file would need to be moved regularly as Enterprise events based upon file are reliant upon the file being created. A modification/update of the file would not work. It must not be there initially or the event will not trigger.