Use Cases for Adding a Relation Extension You create a relation extension when you want the user to receive information about other vSphere or custom objects, either in a list view or in the object navigator, when they select or focus on a given vSphere or custom object. For example, if you created a chassis object type, it might contain one or more host objects. You can create a relation extension for the chassis object so that information about any related host objects also appears in the object workspace or object navigator when the user selects a chassis object. You can add a relation extension to the vSphere Web Client to create a new relationship between a given type vSphere object and any other object type in the virtual infrastructure hierarchy. If you add a new type of object to the vSphere environment, you must create a relation extension to place your new object in the graph of vSphere objects, and to populate the Related Items views. You can also create a relation extension for two existing vSphere objects that do not have an existing relationship. You might create such a relation to take advantage of the Related Items views in the object navigator and object workspaces for those objects, or if you created an object collection node for an existing object in the object navigator.