I think it's difficult to combine a mixer with an interview. The whole point of a mixer is to bring people together in a casual, social setting. They are there to talk and meet people. Trying to get everyone to be quiet for an interview in this setting is unrealistic. If you want to have the interview as well, do it in a separate room with seating, preferably before the actual mixer. Or, don't do the interviews at all. You don't need something like that to have a successful mixer. Leave the interviews for the seminars.