Hi,
You need to include a datasink step within your datasource loop. The datasink allows you to store values from the current iteration.
Once the datasource loop has completed, then you can use the file generated in the earlier datasink step as your second datasource loop.
Here is a link to SmartBear's own docs...
Have a read of some of these recent and vaguely similar posts.
Unable-to-write-response-in-Excel-using-Datasink
/how-to-export-SOAP-API-response-data-to-an-excel-file-in-SOAP-UI
One-Excel-Datasource-and-Multiple-Test-cases-using-Specific-Test
