All of that said, that UPnP is not part of the Z wave standard. Vera does support it, but that was a decision by that company. The SmartThings implementation is limited. And it has nothing to do with being a Z wave secondary controller. So while you should be able to add smart things as a secondary to a vera, you’re not going to get UPNP integration that way. You have to set up a separate integration.
See the following thread: The folks there should be able to help if you want more information On going that route.