I was very pleased to read your message. The sheet music brochure sounds very interesting; I don't know if I'm related to Carlos or José Espinosa de los Monteros, but it is possible that there exist some form of relation because it's not a very common surname.
I know very little about my Espinosa de los Monteros ancestry, since I only know of one ancestor that carried the surname and donnot know her parent's names. She was my great-great-grandmother's mother, and her name was Micaela Espinosa de los Monteros. That, and the fact that she married Benigno Vallarta is all I know.
One thing I know is that the surname has a toponimic origin, which is to say that there is a small "pueblo" in northern Spain that is named Espinosa de los Monteros; the town is in the northern part of the region named Burgos, not far to the south of the region named Cantabria and the province of Santander.
It is very possible that this is also the origin of the surname Espinosa; I know a person who is surnamed Espinosa, and she told me that her surname used to be Espinosa de los Monteros, but had been shortened to Espinosa some time back.
I also have three questions for you, which are the following: Why do you have five surnames? Is Espinosa Delgado a single surname? And, where are you from? :)
As for me, I have three surnames. The first one, being composed of two surnames, is Martínez-Celis; this is my father's surname. The second one, is Greenham;it's my mother's maiden surname. And I live in Mexico City.
Well, I'm looking forward to hearing from you. Good luck and God bless you, too!