Unfortunately, probably not.  I think you are running up against the two-pass limit.  You may be out to pass four or five, actually, but that's beside the point.

One alternative may be to find some way to put the information you need back into the data source for the main report.  Does the data for the main report and the data for the subreport come from the same database?  One solution may be to add another join to your data source, joining to a simple aggregate query of the subreport's source.  For example:

SELECT Main.CustomerNo, Main.DocumentNo, Sub.UnitTotal
FROM Main
LEFT JOIN 
    (SELECT CustomerNo, DocumentNo, SUM(Unit) AS UnitTotal
     FROM SubReportSourceTable
     GROUP BY CustomerNo, DocumentNo) Sub
ON Main.CustomerNo = Sub.CustomerNo
     AND Main.DocumentNo = Sub.DocumentNo

Does that help?

I have not worked with the JD Edwards software. However, keep in mind that you can create SQL queries in Crystal Reports. You can add a Command object and place the query in it. If you have not tried this give it a go it might just work. In about 2 minutes you will know....