If required, the shape of a join and direction can be changed.
To change the shape of a join:

Right-clicking on the join and choosing Foreign key join shape. Then the required side of the join and the join shape can be selected from the sub-menu.

To change the direction of a join where multiple relations are shown as one link in the diagram:

1. Right-click on the link and choose Foreign key join shape:
   
2. From the Choose foreign key join dialog, select the relation from the drop-down list and click OK:
   
3. From the Select foreign key join shapes, select the join shapes and click OK.