I had an idea to generify email templates like we have document templates 

ie Create default header and email templates that are included as subreports.  

Initial this worked I had created an email template like below.

The datasource for the subreports was 

$P{dataSource}.getDataSource("customer")

While this worked when the parent report was supplied with an ACT.

This fell over as soon as I wanted to create the generic template.  We set the datasource as $patient in the template settings in Open and the subreport is set to pass the datasource is

$P{dataSource}

  However, this fails.  It appears the subreport doesn't fill.  We changed the subreport because we can't guarantee the context.

Any tips to get this up and working.