The current IG supports inclusion of the PreAuth number at the claim level (not line level) and that is sufficient for a first iteration of the PCT IG.  Prior Authorization is a separate process from Cost Estimates and so this information may or may not be available at this time in the workflow for a provider to share with a payer at the time of GFE Submit.  Should the community see a need for more information for pre-auth numbers at the line level, we can explore that addition in a future IG with a new ticket.