Resolution:
We can merge an EAR file with a deployment descriptor file to generate a final XML file which contains the values changed in the deployment descriptor file to that AR file using the following command:

AppManage -export -out c:\sample-final.xml -ear c:\sample.ear -deployConfig c:\sample-dd.xml

This will merge the changes done in the deployment descriptor with the EAR file with an exemption for instance level variables. Instance level variables cannot be merged using the above command. These variables are ignored.