I'm not sure if you're interested, but I was looking through the internet to see if there were any Acevedo's out there and I found your messages to be the most interesting. Seeing that you want to know the history of the Acevedo family, I have some information that may be able to help you. I am one of the Acevedo descendants from Spain and I am currently in Spain.
The name "Acevedo" is a very ancient and noble name in Spain, and most researchers say that it originates from Portugal, but even though they say that this affirmation is exact, they say that the actual name originated in France. The first knight to come from the family was "Arnaldo de Bayan", who came to Spain in the year 983 AD to fight against the Moors and he settled in Galicia, near the border with Portugal. Here is where the descendants began, so he is considered to be our forefather. Unfortunately he died in battle against the Moors near the city of Viseo or Buco. His son was the knight who served under King Fernando "the Great", with the name of Gosendo Arnaldez, and it was the son of his son (his grandson) who settled in Portugal and took the name Acevedo from a place known as "of Acevedo" ('de Acevedo' in Spanish). His descendants then bore the name Acevedo. His father's name was Egas Gosindo Bayan who married to Ebescua Biegas, but unfortunately I don't have the their son's name, the one who took the name, although I know that he married Sancha Perez. They had two boys, Men or Melendo Perez de Acevedo and Fernan Perez de Acevedo. One of the brothers, Fernan, went to Spain to serve under King Alfonso VI and helped in the conquest of Toledo, creating many descendants there; noble knights with the name Acevedo de Castilla. It was his brother, Men Perez Acevedo who bore the descendants in Portugal.
Then, the Acevedo's spread all over Spain and Portugal. From these descendants came more, including Juan Bautista Gonzalez de Acevedo, who was the Acevedo who went to the Americas and began the Acevedo line there. He went as a governor. He was also the General Inquisitor Bishop of Valladolid and president of Castilla, while other nobles included Juan Gonzalez de Acevedo, who entered the Order of Santiago ('Orden de Santiago') in 1608.
Other branches also formed in Mexico and other parts of Spain.
I hope this might help you out to form the oldest parts of the family tree. I also have in my possession the family crest, so if you don't have it and you would like to have it, then please advise and I'll send it to you (by e-mail).