In the Navigation Pane, click Settings.
Under Customization, click Customizations.
In the Customization area, click Customize the System.
Under Components, expand Entities, and then expand the entity you want.
Click either 1:N Relationships or N:1 Relationships.
In the main pane, in the Type list, select Mappable.
Select a mappable relationship. Then on the Actions toolbar, click Actions, and then click Edit.
Under Related, click Mappings.
For each new mapping, on the Actions toolbar, click New.
In the Create Field Mapping dialog box, select the source field from Source Entity Fields. Select the target field from Target Entity Fields.
When you select fields, consider the mapping requirements.
Both fields must be of the same type and the same format.
The length of the target field must be equal to or greater than the length of the source field.
The target field cannot be mapped to another field already.
The source field must be visible on the form.
The target field must be a field into which a user can enter data.
If the fields are option set (picklists), the integer values for each option should be identical.
Address ID values cannot be mapped.
Click OK.
Click Save and Close to close the Relationship form.
When your customizations are complete, publish them:
To publish customizations for only the component that you are currently editing, on the Home tab, in the Save group, click Publish.
To publish customizations for all unpublished components at one time, click Publish All Customizations
