When you open a record you can quickly use the menu tiles to navigate to related records. Which related records and the order in which they appear can be customized on the form. In 2015 with multiple form views available this means that depending on the form the user is on, the menu tiles and their order can vary.
2. Click the downward arrow next to Entities
3. Click the downward arrow next to the entity you want to edit and click Forms.
4. Open the form you want to edit.
5. Double click the left side column of the form edit page to activate the Relationship (menu tile) editor.
8. To add relationships you can look to the right side Relationship Explorer menu.
You can then drag the desired relationship into position.
You can also double click the desired relationship to move it to the right and then drag and drop it into a specific position.
9. Click Save.
10. Click Publish.
Your changes should now be reflected whenever a user is on the form you have updated. If you have multiple forms and want these changes across those too, you will need to make the changes to those forms just as you did here.