Simply pick the first and second category, you can also choose elements by level or get all levels then click on the join operation you need
(Join, Unjoin, Switch join and the special Join & Switch tool).

You can also use the optional view tool to isolate the categories involved in the operation for better overall control. 

The installer that ran when you downloaded this app/plug-in from Autodesk App Store will start installing the app/plug-in. OR, simply double-click the downloaded installer to install the app/plugin.

You may need to restart the Autodesk product to activate the app/plug-in.

To uninstall this plug-in, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. OR, click Control Panel > Programs > Programs and Features (Windows 7/8.1/10) and uninstall as you would any other application from your system.

Please feel free to contact us if any problem occurs or if you have some suggestions to improve our software on: support@bimwithit.com