Can I use RQM REST API to link an RTC story to a Test Case?

I am trying to update the RQM test case to link to RTC work item.  However, I am only able to update attributes of the test case but not able to update the link (e.g. using oslc_qm:relatedChangeRequest).  Would appreciate if you provide an example of what the XML input looks like?
I also tried updating the RTC work item and link it to RQM test case using the following XML but existing links are deleted and replaced with nothing..

<?xml version="1.0" encoding="UTF-8"?>

<oslc_cm:ChangeRequest xmlns:oslc_cm="http://open-services.net/xmlns/cm/1.0/" xmlns:dc="http://purl.org/dc/terms/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:calm="http://jazz.net/xmlns/prod/jazz/calm/1.0/" xmlns:rtc_cm="http://jazz.net/xmlns/prod/jazz/rtc/cm/1.0/">;

 <oslc_cm:testedByTestCase rdf:resource="https://<server>/qm/oslc_qm/contexts/<contextID>/resources/com.ibm.rqm.planning.VersionedTestCase/_BfhhgwC2EeWDf4S33X1zJw"/>;

</oslc_cm:ChangeRequest>

Hi Gary,

Try:

<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF
  ...>
 <oslc_qm:TestCase rdf:about="https://<QM host>:<QM port>/<QM context root>/oslc_qm/contexts/QM <project area UUID>/resources/com.ibm.rqm.planning.VersionedTestCase/<test case UUID>">
  ...
  <oslc_qm:testsChangeRequest rdf:ID="n0" rdf:resource="https://<CCM host>:<CCM port>/<CCM context root>/..."/>
    ...
 </oslc_qm:TestCase>
 <rdf:Description rdf:about="#n0">;
  <dcterms:title>1342: Demo Story</dcterms:title>
 </rdf:Description>
</rdf:RDF>