This guide explains how to add fields to objects within a template. During data migration, only the selected object fields are migrated.
Perserving Relationships
To preserve the link between parent and child records during migration, migrated child records must include the Relationship Field that connects them to their parent. This applies to both Master-Detail and Lookup relationships. To learn more about this, see the following article.
Data Masking allows you to mask sensitive fields during migration by replacing them with random data before they are copied to the target organization. To learn more about Data Masking and how to apply it to a field, see the following article.