Use the Generate Layout tool to add ductwork for additional components.
Use the System Editorto add the component to the existing system.
Verify that there is an open connector in the system where you are connecting components, and if necessary add a tee to a duct segment to provide the open connector.
Highlight one of the components in the existing system, and press Tab until a preview of the path from the added component(s) to the existing system displays.
Click Modify | Duct Systems tabLayout panel Generate Layout.