Hi Andrew, pls. look at the "History of El Nuevo Reino De Leon" 1577 - 1723 on the internet.It is in English and Spanish and I think you will find very interesting information about the name Montemayor and where they think it originated.It tells how that name fist came to Mexico. It was translated into English by Edna G.Brown of Corpus Christi and written by Eugenio Del Hoyo of Mexico. Pls. let me know if you find it.