That would be your (simplified) "torque.ditamap":
<map>
<topicgroup>
<topicref href="topic1.dita" navtitle="Topic 1" />
<topicref href="topic2.dita" navtitle="Topic 2" />
<topicref href="topic3.dita" navtitle="Topic 3" />
<topicref href="topic4.dita" navtitle="Topic 4" />
</topicgroup>
</map>
Your actual main ditamap would just have the following where you want to have your torque topics:
...
<topicref href="torque.ditamap" navtitle="not relevant here" />
...
So that basically would "include" your torque map wherever you need it.
Regards
Sirko