In addition to collections and tags, a third way to express relationships between items is by setting up “relations”. Relations can set up between any pair of items in a library (it is not possible to relate items from different libraries).
To create a relation, select an item in the center pane and go to the “Related” tab of the right pane. Click the “Add” button, and select one or more items from the same library in the pop-up window (hold down Ctrl or Shift [Windows/Linux] or Cmd or Shift [Mac] to select multiple items) and click “OK”. The selected items will now show up as related items in the “Related” tab, and clicking an item will take you straight to that item.
With the Zutilo plugin, you can also select multiple items in the center pane, then right-click and choose “Related selected items” to related all selected items to each other in one click.
Note that when you relate item A to B, B will be automatically related to A. But relations are not transitive: relating A to B, and B to C, will not automatically relate A to C.
Some suggestions of how you could use this feature: