The balloons you have seen at the Jamboree are owned and operated by a scouting family from Louisiana. They come to the Jamboree as quasi staff and tether at the arena shows and a few other locations. Same for the Army balloon although the pilot of that aircraft is/was on an Active Guard/Reserve tour in support of recruiting command. If you could not guess from my screen name I'm also a balloon pilot. The G2SS rules are that no scout is to RIDE in a hot air balloon tethered or not. Ride is the key word. The balloons are on display and no rides are available. Contact your local balloon club or the Balloon Federation of America to locate pilots in your area who might be enticed to tether at your event. I will caution you that a large space is needed for each balloon and I would offer to refill the pilots propane tanks for him/her. A typical 1 hour inflation will use 3 tanks of propane (generally 10 gal fork lift style), depending on ambient temperature. One more note, a few years ago New Jersey enacted some restrictive laws concerning the operation of Lighter than Air Craft, Free Balloons in certain areas. I dont recall if it was state wide or localized so check with a local pilot. I hope this sheds some insight to you question and as balloonists say Soft Landings