3816639 - Will activating the 'Generate an External ID when a new attendee is created by a user' generate External ID for attendees that were already created?

We would like to perform an Attendee Import to update several attendees already created on our system.
To perform the updates on the created attendees, we need to update them based on the External ID.
However, we currently have the Generate an External ID when a new attendee is created by a user option disabled on our Attendees Settings.



We would like to know if by enabling this option, an External ID will be generated for the already created attendees, so it would be possible to update these already created attendees through an Attendee Import.

We would like to update attendees through import but they do not have an External ID. , KBA , CON-EXP-ADM-ATN , Attendees , Problem