If the subreport will be linked to the main report, make sure the underlying record sources (record source: The underlying source of data for a form, report, or data access page. In an Access database, it could be a table, query, or SQL statement. In an Access project, it could be a table, view, SQL statement, or stored procedure.) are related (relationship: An association that is established between common fields (columns) in two tables. A relationship can be one-to-one, one-to-many, or many-to-many.) before using this procedure.
Create a subreport in an existing report
Add an existing report to another report as a subreport