Good point sometimes there really isn't a rhyme or reason. Sort of like Sachse and Rowlett are Garland ISD but not called Garland Rowlett or Garland Sachse. La Vega is in Bellmead but is called Waco La Vega.
Isn't Clear Brook actually in Friendswood but part of League City ISD?
Maybe after time Alvin will be dropped once Shadow Creek has been opened a while. I remember when I was younger and the Woodlands was often referred to as Conroe The Woodlands.