Add updated form respondents to scheduled event attendees list

Registration form updates aren't added to the event attendee list, causing missed invites and prep overhead. Add respondents to the event list so coordinators can confirm attendance ahead of sessions.

Overview

When registration updates don’t reach your session event, coordinators miss invites and scramble to confirm attendance. This flow adds respondents to the event attendee list automatically so program coordinators can confirm attendance and prepare materials within minutes.