Patrick Roth looks at a customization issue with the new Word Report Templates. The issue was resolved and Patrick tells us how in Using 3rd Party Series Reports in the Report Template Maintenance Lookup Window.
Using 3rd Party Series Reports in the Report Template Maintenance Lookup Window
Reporting & BITips & Hidden Features
Archived post from 2010. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.