Can we define different levels of execution subsets within RQM?

Does RQM support defining different groups of test cases, so that the groups can be arranged in various parent-child relationships where any group at any level can be distinctly executed?

A theoretical example will help.

Let's say at the topmost level we want to define a set of SQL tests.  Within the SQL group are any number of second level subgroups such as Selects, Inserts, Joins, etc.  The Join group may further divide tests into a third level of groups such as Left, Right, Inner, etc.

Given that we have configured RQM to use a custom adapter to automate test execution, we wish to execute the entire set of SQL tests as a whole or any subset of tests, such as only the Join tests, or maybe just the Inner Joins.  Regardless of which level we initiate the test execution or even how many levels of test groups exist, we want to auto-execute tests at that level including all sub-levels and have RQM summarize the results for all the tests.

This works fine if we only have independent groups of tests that are not hierarchically related, since we can place tests for each area under their own suite and then execute the suites within RQM.  But there doesn't seem to be a way to set up multiple levels of parent-child relationships between test groups with the intent to execute them as a whole or as individual parts at different levels of granularity.