Start by clicking on the users who are present. You can mark this if they are not present but have notified an absent. Then you can choose their function at the meeting and who will be the secretary and one or more adjusters (also mark the chairman as a reviewer if he/she is to review).
Board members invited to the meeting are always listed from the start, but both these and other names can be removed completely from the attendance list by clicking on the icon with three dots and selecting "Remove" on the far right.
Should additional people be added, press the "Add person to meeting" button at the bottom left.