Manually add bookings

Is it possible to manually add bookings. Some older people wanted to follow a class that can be booked on our website with the Booking Activities plugin, but they can’t figure out how to do it. We agreed on everything on the phone. but now for everything to be clear and to avoid mistakes we want to add them manually to the bookings-list in our backend (so they get notified 2 days in advance + the number of bookable slots is up to date).