I use the copy testcase option a lot to clone testcases to a new suite. I want\need the order to be preserved. I'm most often copying one suite of testcases to another, and I need the order of the testcases to stay intact.
Here's the doc that I'm referencing:
https://docs.microsoft.com/en-us/azure/devops/test/new-test-plans-page?view=azure-devops
Specifically the Copy/clone test cases (new capability)
