If there is no .qvw extension, the 'xyz' file should not be recognized in the QMC, then it is impossible to add doc CAL to it at the beginning. So file 'xyz' should have .qvw extension. Maybe you hide the extension.
Have you tried to add 'xyz.qvw' back? And are you sure you add the file in correct path?
One thing I have found that has worked in the past is using the QlikView Server Cal Manager app.
Make sure you read through it, but this should be able to help with what you need.