I am working on pushing my changes to a git repo so they can be pulled in, but one thing that is quite different is that instead of looping over the quantity supplied by the user and creating individual tickets, I have 1 ticket with the number of people attending. All the metrics still update appropriately, but it allows for the needs my customer had to be met so that a user can RSVP for 4 people, but there is just 1 record to maintain. There is the ability to change the quantity by the user on the front end by re-entering their name and email exactly the same as the previous RSVP and just change the number.
Here is my repo for the changes. This does include the phone number addition.
I am not quite sure what it would take to change my code back to function like the existing plugin where 1 ticket is minted per RSVP.