rootPersonId is added by Identity Sync and refers to the identity on origin server. mergeWith is used to refer to parent of merged face identities.

mergedWith indicates the record is a child of another record.

• The parent record will have hasMergedPeople=true

rootPersonId indicates the person ID on an origin server that a record was sync’ed from

• You will always see this on destination sync servers
• This parameter will also be added on origin server when record created without image (i.e. thru "Add" button i Person window)
• If rootPersonId is not present, then it is equal to the personId