Actually I am in the process of doing that for 2 rooms. You will need their booking number and last name, DOB, emergency contact, their email address and physical address, emergency contact information and relation, how are they arriving at the port, bed configuration, passport information - issuing office, exp date and issuance date, number, accept their contract for them. Most importantly select their arrival time. You can oy do any of this when it is their time to check in.