Sharing of itineraries is treated quite separately to that of sharing tracks, although when viewing an itinerary map you can choose to see the track points shared by others even if you haven’t shared the itinerary with them. In fact this is the only place where you can view and monitor the progress of multiple users.
To access itinerary sharing, select the Sharing menu option from the
Itinerary tab of the the itinerary page.
The list of any existing itinerary shares is displayed. You can choose one or
more of the shares and click Activate or Deactivate buttons to
change their activation status. You can also choose to delete the share,
although this has the same effect as simply deactivating the share, but
additionally removes the nickname from the list.
Click the New button to start sharing the itinerary with someone else.
Enable the Active checkbox to actually enable sharing.