I checked UIL's website, here is what ot said
(A) Should three or fewer 1A varsity bands in a region receive a division 1 rating, any conference 1A varsity band that has followed the procedures established by the Region Executive Committee to indicate to the Region Executive Secretary the intent to advance to state and that receives a Division 1 rating at the region contest shall be certified for advancement to the state contest.
(B) Should four or more 1A varsity bands in a region receive a division 1 rating, all 1A varsity bands in the region receiving a division 1 rating shall be ranked using the procedures outlined on the UIL website and the three 1A varsity bands receiving the highest ranking shall be certified for advancement to the state contest. In Addition, one band for each two bands receiving a division 1 rating ranked below third place shall be certified for advancement to the state contest.