Here are the steps required:
- Create an internal-only item for the admin charge
- Go to Step 8 of the event setup
- Click Edit
- Create a new item and name it as the charge reason accordingly by following steps here: Create New Products for Additional Purchases
- Select Internal as Availability by following steps here: Change Availability Restrictions for Additional Purchases Products
- Note: Please ensure to set it as Internal so that this item will not be appearing during the public-facing online registration process
- Apply manual charge to existing registrants
- Open an individual participant page
- Add charges by purchasing the admin charge item created at Step 1 by following steps here: Add Purchases to Existing Registrations