How to chunk topics within slave ditamaps?

In order to publish to HTML, I am using dita and xml. I have a parent ditamap (book map), which includes multiple ditamaps, each is a chapter, including individual dita topics. I would like to chunk these dita topics, which as said are inside the chapter ditamaps, such that each chapter appears on one HTML page. Otherwise, each individual topic appears on one HTML page. 

I tried chunk="to-content" in the chapter ditamaps, as an example:

<map>

 <topicref keyref="introduction_computed_tomography" type="topic" chunk="to-content">
<topicref keyref="xray_basics" type="topic"/>
<topicref keyref="computed_tomography_basics" type="topic"/>
</topicref>

</map>

This chunks the individual topics but the links and figures are gone. Is there a better way of gluing the topics inside the ditamap together?