Hey,
We're glad that you managed to find the host with your tickets without too much trouble. Our apologies for any confusion that might have been caused while making the booking. However, for Exclusive Partner Access at the Vatican, the fare for a child and adult are exactly the same, hence we do not provide a field to add children to the booking. This is not a lapse on our part but rather a deliberate aspect of our website.
Had you booked normal Skip The Line entry tickets to the Vatican, your child would have been eligible for a reduced fare and the website would have allowed you to register your child accordingly. We apologize once again for any inconvenience caused and hope that this information clarifies your doubts comes in handy in the future.
Sincerely,
Viraaj
Head-Customer Success