I had that happen; I volunteered to give a talk at a faculty seminar so they'd know the students' point of view and before I was chosen the four school/faculty planners called and did a conference call with each applicant, to see which to pick. So, some didn't get picked even though they volunteered. But then, some of our people who were picked didn't show up for the meeting we had a week before the conference to coordinate how we were going to speak, what topics, etc. So, perhaps they could call you if someone chosen gets cold feet.