RE: [dita] Conref push in a DITA map?

I assume the question is about pushing a topicref element, e.g. in
example fribblewhiskets.ditamap

<map id="fa" title="Fribblewhiskets">
 <topicref id="a" href="Fribblewhiskets.dita" type="topic">
  <topicref id="b" href="Fribblewhisket_internals.dita"
type="concept"></topicref>
  <topicref id="c" href="Fribblewhisket_configuration.dita"
type="task"></topicref>
  <topicref id="d" href="Fribblewhisket_corroboration.dita"
type="task"></topicref>
  <topicref id="e" href="Fribblewhisket_LEDs.dita"
type="reference"></topicref>
  <topicref id="f" href="Fribblewhisket_FRUs.dita"
type="reference"></topicref>
 </topicref>
</map>

Example newfribblefru.ditamap:

<map id="fb" title="New Fribblewhisket FRUs">
 <topicref
         href="Fribblewhisket_new_FRUs.dita" type="reference"
         conaction="mark"
         conaction="pushreplace" 
         conref="fribblewhiskets.ditamap#c"/></topicref>
</map>