Varying the test case (request) in Load UI

I have been looking into property expansion and how you can effectively run the same test on a number of different URLs by referencing them in a .bat file.
The problem I have is that I need to make different requests to the same URL. (I need to send different xml).
The test I want to do is the same in every other sense, so same load level and time etc.
So I have all of the separate requests I need to make to the URL set up in different test cases in SOAPUI and they appear in the Drop down in LOADUI when selecting a test case to run and it's this that I need to vary via a .bat file as opposed to varying the URL for a specific test.

Is there any way of achieving what I want?

Thanks