Is there a way to add parameters to a list of test cases?

There is not a way to do this through the UI (currently). One idea in the future is to have a SpiraApp that will let you script actions inside the app, but that is not yet possible.

Probably the best way right now is to use our API to script this kind of mass change. I can provide some sample code if that would be helpful?

Yes please. I'll give it a try.

Any news on that sample code?

Sorry for the delay, here's the API endpoint to use:

https://api.inflectra.com/Spira/Services/v7_0/RestServiceOperation.aspx?uri=projects%2f%7bproject_id%7d%2ftest-cases%2fparameters&method=POST

and the sample body would be:

{
"TestCaseId":123,
"Name":"myparameter",
"DefaultValue":"somevalue"
}