Also, as the director, you must try to schedule your sectional times around their practice schedules. There are many times that I have to schedule two trumpet sectionals, one for 7th grade athletics and one for 8th grade athletics.
In the end, the kids have to see that you are serious about the sectional and you are willing to make it work.
Last, but not least, you need to keep building relationships with your coaches and your admin. It's up to you and the coaches to work out the schedule without the kids in the middle.