How do I tell Z-tool which network to incude with

[mikee123]

I need to split my network , and want to create a separate network. I already installed a second controller (not as a secondary but another primary). Now I want to start excluding devices from my current network, and include them to my new controller. How can I choose which controller to use in Z-tools ? When I use Z-tools, I get the option to select the HS3 installation, but both networks are on the same HS3 installation.
Hope that makes sense...