I've probably approached students in the band hall to ask if they need help with anything but never demanded they need to get their horn out or play something off. It doesn't bother me as long as they aren't running around in the band hall.
In the mornings they require all high school students to sit in the gym foyer to eat breakfast. Otherwise, they need a note to leave. In the afternoon athletics dominates everything. I do have a few kids that could come in but haven't won them over.
During lunch, they have 25 minutes and are required to go to the cafeteria. I have a junior high class while they eat.
Thank you for the suggestions. I hope I can get more kids to come after school.