The Instances Panel provides some helper tools to make working with instances easier.
Select by data: Selects all objects with the same object data (mesh) as the currently selected object. You could, for example, place objects around the scene using
D to create duplicates with shared mesh data and then select all of them.
Rename selected: Instances that have the same mesh should also have the same name. This renames all selected objects to the name entered in the text field above.
Select by name: Selects all objects that contain the name entered in the text field above.
Mark as Instance: Sets the is instance property for all selected objects. These objects will then be exported when exporting to
Remove Instance property: Removes the is instance property for all selected objects so they won't be exported when exporting to