I do not believe we have a feature to support that requirement. But depending on where and how you are calling this RD, it's possible you could wrap it in your own custom activity to handle this logic, so that when your RD is eventually called, you've already accounted for your "Ram" scenario and passed the appropriate params and the RD does not have to be modified at all.
Are you trying to substitute .Name == "", or .Name is NULL?
If the former, you can use the Replace function alias.
If the latter, I'm not sure it can be done within the report definition rule, as "IS NULL" is not the same as "== NULL" in SQL. You may have to create a separate version of the RD with .Name IS NULL as the filter criteria, and determine beforehand to call it if Param.Name == "Ram".