Externally defined report-level properties

I know from here that it's possible to set certain properties at the report-level in the JRXML, and it is possible to do so at the application level by modifying webapp/WEB-INF/classes/jasperreports.properties (or any properties file in/below that folder), but is there a way to define an external resource in the JasperReports Server repository that would contain properties shared among a number of reports but not all reports? I'm looking to do something similar to how you can define styles in a .jrtx and then use that file repeatedly.

Thanks for your help!