if you create the data in the backend then it’s a bit tricky to get it to save on a state in the front end
you can create and save on a state in front end
user can plus each item to a list
or
use a plugin to create and add to a list on front end
if page data is reservation then you just need 1 repeating group on the page to show the guests
the source of the repeating group data is either
search for guests where reservation is pages reservation
or
pages reservations guests list
depending on how it’s stored