Allan,
Despite the "Barnwell 19" designation--which is named for the county, not the school or city--Blackville-Hilda is a completely separate school district and has no affiliation with Barnwell High School. Believe me, I grew up in Blackville and used to work and coach at there--there is a huge rivalry between Blackville and Barnwell that goes way, way back. I'm really sorry to hear about your injured player--hope she makes a full recovery--but I seriously doubt it was a "favoritism" call on the official's part.
Oh, and I agree--it amazes me that a county the size of Barnwell has three completely separate school districts, while one the size of Berkeley is all consolidated into one.