Adding a guest to a hotel reservation is usually a straightforward process, but the method depends on how you booked. If you booked directly through the hotel's website or app, you can often log into your account, find the "Manage Booking" section, and update the guest count or add a name to the "Additional Guests" field. If you booked via a third-party site (like Expedia or Booking.com), you must usually contact their customer service to make the change. However, the most reliable way is to call the hotel's front desk directly. This is important for several reasons: many hotels have strict fire code occupancy limits, and adding a person might require a room upgrade (e.g., from a King to two Queens). Additionally, adding their name to the reservation ensures they can check in or get a replacement key if you aren't present. Be aware that some hotels charge an "extra person fee" per night, especially at resorts or all-inclusive properties, where the rate is calculated per head rather than just per room.