After launching a campaign, it is always possible to add participants to it.
In the Interviews > Interview Tracking section of the left menu, click on the relevant campaign and then on the blue button "+ Add an interview".
Enter the first name followed by the beginning of the last name in the search bar to find the concerned employee, then click on their name displayed in the dropdown menu. You will be able to change the evaluator of the interview before confirming.
💡Note: If the interview campaign type is Occasional Interviews, you will also need to enter the start and end dates (which will correspond to the signature deadline) of the interview.