Here's how to provide high level information on an itinerary only, to start, and then later share more details in more of a "final itinerary":
Step 1
Create your general, high-level itinerary and save it (and share it with your client)
Step 2
When your client confirms their trip, advance the file by clicking the 3 dots on the file level and select "Move to Confirmed"
Step 3
Duplicate that high-level itinerary by clicking the 3 dots on the file level and adding a note for yourself in the Internal Itinerary Notes section that says something like "FINAL ITINERARY"
Step 4
When you are ready to share the Final Itinerary, move the file back to Pipeline (from the 3 dots on the file level) and then move it back again to Confirmed (3 dots on file level) and now check the FINAL ITINERARY as the itinerary to be confirmed
Step 5
Share the new link to the Final Itinerary with your client
Step 6
Deactivate the itinerary link for the original high-level itinerary from the 3 dots on the file level of the original itinerary
Note: if you had already created a guest portal attached to the high-level itinerary, it will automatically re-attach to the new confirmed Final Itinerary.