I have a set of manual test cases in QC which are getting automated now. Is there a way to link the automated test cases to the manual test cases. I want to do this to set up a mapping between automated and manual test cases.
Do you want to keep the manual and automated test separate, or incorporate the automation into the originally manual test? What tool are you using for automation?
If you want to incorporate the automation into the originally manual test, go to the Design Steps tab for the test case. Pull down the Generate Script toolbar button. This will give you options for the type of automation script you want to incorporate. Paste in the automated script accordingly into the Test Script tab that subsequently becomes available.
If you want to keep the manual and automated tests separate and discrete except for the link, I don't think there is any generic linking functionality available in QC. You could possibly create some custom fields in the Test entity and fill them with cross reference information, or just use the Description field of the Test Case.
If you don't have a one to one mapping between your automated and manual tests you will probably have to keep them separate or replace them. I have in the past used an additional field to maintain the mapping and a tool I wrote to update the execution status of the manual test cases from the automated ones so that a common reporting solution could be used. I had to maintain the mapping in test lab from the automation side as the mapping depended on the data used to execute the automated test.