You can add a reviewee to an already launched campaign from the page of the relevant campaign:
1. Click on the tab Performance > Campaigns and select the desired campaign.
2. Click on the three dots in the top right corner and select Add reviewees.
3. In the new menu on the right, start typing the first letters of the Reviewee's name and select them in the drop-down menu.
4. Click Launch reviews.
Once invited, the Reviewees receive an invitation to prepare their interview.