To create a relationship in BPMN, there are two options:
 | Fast draw. If you pick one object from the menu, it will automatically draw a relationship between an existing object and a new one. |
 | Relationship tool. With this feature you can draw a relationship between two objects that don't have a relationship between them yet. |
Here you can see how the fast draw works:
Below you can see how the relationship tool is used:
