Bryon,
you should have a look at the topicgroup, topichead and topicset elements in the DITA spec. Depending on the desired structure you might either want to use topichead, which would include a section title for your "grouped" topics or topicset, which provides a unique ID (for re-use) for your group of topics but doesn't add another level in the TOC. Instead of topicset you could also use topicgroup which is suitable when the topics within that element can be re-used in different contexts (meaning there could be different topics before or after on the same TOC level). But I guess what you are after is the topichead which would provide you the possibility to set a section title for you group of topics.
You then insert the map containing one of the wrapping elements and the topicref's to your 4 topics using a plain topicref element.
I hope that is the kind of information you have been looking for.
Kind regards
Sirko