Update Parallels on your Mac first then use Compose to create a .PKG of the application. Deploy the .PKG to everyone that needs the update. Make sure to allow the users to defer the update and create a message saying that they need to quit Parallels first before starting the upgrade.
You are welcome to use my updateTool. It can update any application without the need for admin credentials due to a privileged helper.
https://github.com/tmhoule/AppUpdateTool New version was recently released.