Migrating data to Salesforce and mass updating records can be challenging, but you can make your life a lot easier with the create audit fields feature. Creating records through the API will now allow you to update standard audit fields such as LastModifiedBy. In addition, you will be able to update records with inactive owners without contacting Salesforce.
Two different permission sets, “Set Audit Fields upon Record Creation” and “Update Records with Inactive Owners” can be assigned to users. This is a safeguard to ensure that only qualified users are defining the audit field and manipulate sensitive data. These permission sets take the place of what used to be a longer process, where you had to contact Salesforce to update inactive records.
-Ryan and the CMB Team