To add a relationship to an existing entity, focus on the Relationships pane of the Entity View. Find the row associated labeled with the Relationship type you want to create.
Then using click Add or by clicking the dropdown toggle and clicking Relate Existing Entities.
When the dropdown is selected, add as many entities you wish to relate using the specified type. You can filter the entities being shown by typing into the dropdown text field.
If you need to remove an entity from the current batch of entities to relate, click on the 'X' button of the desired entity.
To cancel adding entities to relate altogether, click on the cancel button above the dropdown adjacent to the label name. This will cancel adding all selected entities to relate.
To stage the addition of all the added relationships, click on the green checkmark. Changes will not be saved unless the Save button of the Entity View page is clicked.
Instead of relating an existing entity, if an entity does not exist, you can create it on the fly by using the same dropdown toggle next to the desired relationship and clicking one of the Create options, depending on the relationship type, certain classes will be available to create on the fly.
Upon clicking the corresponding Create option, fill in the desired attributes the same way you would attributes in the Attributes pane. When you are satisfied with entity relationships, click the Green check button to stage the changes, otherwise, click the cancel button to discard everything.