If you are on a view, you can select an object from which you want to create a relationship to another object. If you select an object, you will see four buttons around it. If you click the relationship tool button , an arrow will appear. If you click with this arrow on another object, the following list will pop up:
Here you see three sections: Use existing, Add new and Add alternative.
Use existing: Shows you all the relationships that are already used in the tenant between these two objects. If you click on them, it will show you a dropdown list with the label of each relationship.
Add new: Shows you all the relationships that are activated and possible between the two objects so you can create a new relationship with a new label.
Add alternative: Shows you the possibility to create a derived relationship according to the ArchiMate rules.