Currently a single test can be bound to only one data source (a single file, a single sheet, etc.). For larger tests that include subtests and passing data to the subtests, the single spreadsheet becomes nearly unmanageablylarge. It would be useful in cases like this to be able to bind the test to multiple data sources (e.g. multple sheets within the same Excel file). Then the various subtests can reference data in sheet 2, 3, 4, etc. while the parent test could use data from sheet 1. This would significantly simplify setting up the data being feed into the main parent test.