I am creating a Journey which will create a Task on a Contact record in my Salesforce Sales Cloud.
The entry point for the Journey is a Data Extension loaded with data from an external source. This data is loaded via CSV import.
The external source has access to the External ID that is stored on my Contact record in Sales Cloud, but it does not have access to the Sales Cloud Contact Record ID.
In theory, this should be possible if Marketing Cloud creates the Task by upsert with the External ID, but I can't determine if this is at all possible.
Has anyone completed a similar activity?