Filter Variable in the child report while drilldown

Hello everyone,

I would like to know if any way out there to filter the variable values in the child report while drilldown from the main report.

Example:

Main Report: Location Wise Sales and Cr.Memo Values
This report shows location wise Sales Amount (Sales Invoice Line.Amount), Sales Quantity(Sales Invoice Line."Quantity (Base)" and Credit Memo Amount (SalesCrMemoAmt-Varaible and the value calculated from Sales Cr.Memo Line.Amount for the corresponding location)

Child Report: Customer wise Sales and Cr.Memo Values
This report shows all the customers grouped by Location when drilldown from the Main report (Mentioned above). Customer wise Sales Amount (Sales Invoice Line.Amount), Sales Quantity(Sales Invoice Line."Quantity (Base)" and Credit Memo Amount (SalesCrMemoAmt-Varaible and the value calculated from Sales Cr.Memo Line.Amount for the corresponding Customer)

On drilldown of Sales Amount from the main report, the child report should show as is attached.
But on drilldown of Cr. Memo Amount from the main report, the child report should show the values filtered by SalesCrMemoAmt <> 0
Note: SalesCrMemoAmt in the child report is a variable and is calculated one

I am stuck in filtering out this variable from the main report on navigation.

Kindly suggest if I could be arrived at the solution.

Thanks in advance.