The Drupal Salesforce Suite and webform documentation state:
The ID of created/updated records are stored with the submission, and can be used in subsequent record updates in the same submission
Source: https://www.drupal.org/project/salesforce_webforms
Sadly I just don’t know how to reference it in the mapping. I first log a Case for the submission and in my second mapping I am trying things like:
[submissions:value:case] [submissions:value:case:Id]
But it’s just trial and error, mostly error – got to be documented somewhere?