Hi Kian,
Thanks so much for reaching out!
At this point, the best method to achieve this is to use a User switching plugin such as https://wordpress.org/plugins/user-switching/
Basically that will allow you to perform the front-end process as that other user.
Better yet, if you are only using RSVP tickets you can do so without that plugin. Simply head over to the event and use the ticket form (entering the attendees email).
Let me know how that works out for you and if you have any other questions on this topic!
Thanks,
Jaime