To change your team size, navigate to the "Account" area of your SendBoard settings. Under the "Plan Details" section, you will see what plan you are on, how many users are included in the plan, and how many Trello users have been allocated to the plan.
Your team size refers to how many users are included in your plan. This is the number of users or 'seats' that you will be billed for.
Allocated team members
Allocated team members refers to the number of Trello users who are currently authorised to use SendBoard. You can't have more team members that your plan allows.
To allocate new team members to your SendBoard account:
Ensure that they are an existing member of your Trello team. Guest users on a Trello board cannot access SendBoard features.
Update your team size in SendBoard so that there are enough available spots.
Notify your team members that they can access the board to authorise SendBoard. You don't need to explicitly add each person to SendBoard.
Increase team size
If you want to add new users to your team, you'll need to ensure that your plan includes enough seats. If you are going to add several new users, set your team size to the total number of users you need. You can do this from the 'Manage Plan" area of SendBoard Settings: click on "Manage users" and then "Change Team Size".
Decrease team size
You can decrease your team size in a similar way. Just ensure that the number of allocated users does not exceed your desired team size. You may need to "Remove" users from your team before reducing the team size.