First, update the booking and edit the departure date from same day booking to multiple nights, marking the departure date when the room block checks out.
Then, follow how to add a room block to a booking steps.
How do I add a Room Block to a Booking That Was One Day?
How do i add Guestrooms to a Booking that was originally just a day Group - How can I change a Booking from 1 day to multiple days?
Updated over a week ago