Pay from user to user

Hello, I am trying to make an app revolving around friends getting together for events. These events could be anything from going on a hike, to watching a movie, or going to a baseball game. The app would provide a centralized place for people to see details for the event, sign up to attend events, or post event. In the case of a group going to a baseball game, they would all need to pay one person (the one who posted the event) who would then buy the tickets for the whole group at once (that way they can all sit together because baseball games have assigned seating). In this case I would either need to collect the payment from all the attendees and then reimburse/pay the person who buys all the tickets, or I would need a way for users to pay the designated ticket-buyer directly. Any thoughts on how to do this via bravo??? Thank you all, lots of love for this community :)