I don’t see a lot of these options on the ST ios app. Perhaps they are different now?
You can add it as a secondary controller, but the smartthings zwave controller does not support controller replication or controller shift. So the results will be somewhat different than if you were adding a second Vera or an Aeotec stick.
Wouldn’t the ST just pass the commands back to Vera in a secondary setup?
If it’s just a pass through, yes. If it’s a controller activity, not necessarily. Search the forums, you’ll see how things have worked for other people. Just depends on what you’re trying to do.