• External Contacts > External Entity > Import permission

After you import external contact and external organization records, you can upload changes to them later. The import process updates existing records based on the key values. For example, suppose that you upload a source file in which contact ID 1 looks like this example:

Later you change Gina’s title in the source .csv file:

The import process updates the External Contacts record for Gina McGuire to show the person’s new title.

Avoid reusing contact IDs

Caution: If you reuse contact IDs, you can replace your previously imported contact information.
Note: In the following example, some fields are resized or hidden.

Suppose that you have this external contact. 

When you reimport the source .csv file, you change the information for contact ID 6.

The import process replaces all the contact information that is associated with contact ID 6. In this example, the import process replaces all the information in the Peter Saunders record with the information for Brian Marks.