Pass Data from SubReport to Main Report

I have a main report mainly has some data being printed in the details section of a report. In the details section I have a subreport in order to retrieve a value from another DB type (one Oracle and another Teradata). I cannot just link the databases together either which is why I have the subreport. In the subreport I have it simply printing the description based upon a number which also resides in the main report. With the subreport in place, the report runs incredibly slow as there are a few thousand (~2-3K) records which effectively need the subreport refreshed each time. Also, in the report header I need this information to print with the numbers in order for it to make sense. I basically just want the subreport to run once and send the values over in a variable if possible. I guess my big problem is not knowing how to properly send data from the subreport to the main report. I can send in reverse by simply linking the field to the subreport. Are there any Crystal Report samples where it has a main report with a subreport passing data to it, and NOT the main report passing data to the subreport?

Example of how I'm looking to present the data and where it resides:

Header-> Product (main report and subreport) Description (subreport only)

What options do I have? Is this a Shared Variable case? If so can a detailed response be given as I find it easier to learning visually on my end rather than extended technical write ups.

Thank you as always!

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