To control the coverage computation, you can use the headingCoverage Tag.
When creating a Requirement Hierarchy Table from the ReqXChanger menu, the headingCoverage Tag is created and set to true.
Set to true, it computes the coverage not only for the Requirements package but also for the Requirements which have other Requirements as children (usually headings).
If the Requirement Hierarchy Table is not created from the ReqXChanger menu, the headingCoverage Tag can be added and set to true to consider the coverage for headings.