Extending report template Entity in multitenant evn

I have used the multitenant add-on in one of my projects where I can not upload Report template as it is only accessible by the Admin. Therefore, I wanted to extend the template Entity to ExtTemplate like I have extended some other Entities like Report, ReportGroup ext. However, the report_template file is not available to extend in the studio as you can see in the following image where only two other Entities under report is available, not the template.


Thanks for your suggestions.