Instead, you'll need to purchase an additional full-fare adult ticket and once you have made the booking, contact us via the chat function on our website so we can link the two bookings and change their passenger type.

Technically, Ryanair does not have a simple "Add Passenger" button for existing flight bookings in the way many travelers might expect. If you want to add an adult to your trip, the standard procedure is to simply create a completely new, separate booking for that individual. However, if you are trying to add a minor (under 16) to an existing adult booking, the process is more specific to ensure they are legally linked. You must first create a separate booking for the child (usually by selecting them as an "adult" to bypass the system's block on lone minors), and then you must contact Ryanair's customer service via Live Chat to have the two bookings linked. There is no fee for linking the bookings, but you will be charged for the new ticket at the current market price. For infants (under 2 years), the process is easier: you can often add an infant to an existing adult booking through the "Manage Booking" section on the website or app for a flat fee. It is important to remember that once linked, you must check in both parties separately. If you need the group to sit together, you should purchase adjacent seats during the booking process, as the system does not automatically re-assign seats for the original party to accommodate the new passenger.