Site admins are capable of registering users for an event, even after registration for that event has closed.
To admin register a user, first go into the event that you would like to register a user for. Then, use the Admin menu on the left side of the screen to locate Registrants. Near the top of the Registrants page is a + Add button. This will take you into the registration flow, in which you will be able to search for any user in the system. You will also have the ability to add a user that is not currently associated with the site. (Note: before creating a new user, double check that the user isn't already in the system).
Admin Registering One User For Multiple Events
For users that need to be registered for multiple events, an admin can link registration carts so that the transaction can be completed all at once.
For the first event that you would like to link, make sure that the user's registration status is "Accepted", and make sure that their payment status is "Not Paid". After saving the registration, it will show the payment highlighted in orange and the word "owed", and next to that there will be a link to "View Transaction".
Clicking on this link will show you the cart number, also known as the"Transaction ID". This is the number that will be used to link multiple carts.
For the second, third, and all future events to link, make sure that the user's registration status is "Accepted" as before, but this time make sure their "Payment Status" is set to "Attach to transaction".
This will bring up a field to let you enter the "Transaction ID" that you saved earlier. Once you enter the "Transaction ID", click "Save Registration" to link the carts. The "View Transaction" link will appear once again with the consolidated cart.