By using the file attribute on the report tag in reportdefinitions.xml file it is possible to configure the application to use another rpt file than the default file.
<report name="VM4040" description="Simple Test Report" group="Test" file="VM4040x.rpt">
Alternatively use the built in Sage 300 feature called Customization Directories.
The second alternative is to create a systems Choice parameter with the name SYS_RPTFILE and specify a fixed set of RPT files the user can select from.
<reportParameter xsi:type="ChoiceParameter" name="SYS_RPTFILE" label="File" systemParam="true">
<option text="Default" value="vm4040.rpt" default="true"/>
<option text="Special" value="vm4040x.rpt"/>
</reportParameter>