If a crew member that had previously been removed from your vessel returns, they can re-join the vessel directly from their workrest app.
To re-join the vessel, when logged into the app, the crew member needs to:
Tap on the vessel icon at the top right of the screen
Select their department and position
Search for and join the vessel
This will then re-assign them to the vessel.
You'll then be able to edit and confirm their start date onboard directly through your month review.