Update all testcases Scripts and its steps in one shot in RQM

Our objective is to update the Test step of a test case script. We have a test automation editor using which Test scripts can be created. It has captions which have the name of steps and expected Value ex :

 Set Voltage = 12

 Check Voltage == 12

Using a tool we can generate an XML file and push to Doors Classic Successfully. And Link via DXL Testcases and requirements were linked with ease. 

We want to achieve the same with Doors NG. Current Plugin of VtestStudio allows to put names of Testcases but not test steps of this. To make Test spec with Test cases and test steps, we made a tool which generates XML file. 

We can modify XML mapping, but No idea - how to push this XML to Doors NG, So that it updates the test cases with test steps.

I worked on a xls plugin to Push to RQM. It always state Export to RQM successfully , But Doesn't update anything.

Any sort of help is appreciate to put more light on this topic.

Thank you very much in advance.