Here we'll explain how to validate the toggle item. For example:

We have an Account with three Products grouped in the report and added the option to toggle:

When we toggle the Account, we have this result:

Notice that the Product is showing in the group, so the report would be messy and confusing for billing calculations for example.

The solution is simple, use the InScope function in the expression. Go to the textbox of the product and add the following expression:

=Iif(InScope("Name of the row Group"),Fields!productnumber.Value,"")

Here is the result:

Enjoy it!