Introduction

Linked reports with Business Units can be created from Pre-Defined Reports with Business Units or a normal report marked with Export drilldown for Business Unit.

Read here about, what is a linked report 

You can Deploy one or more of the Pre-Defined reports for the Business unit to Reporting Services. Deploy them to the Business Unit Template folder.

You can also Create a report, and when deploying to Reporting Services, Enable drilldown and Export drilldown for Business unit. Deploy the report to the Business Unit Template folder.

This will create a property for the Business Unit, which is needed for using it with Linked Reports.

Now go to Create linked reports