I think it was Lamar Fike, who "collaborated" with Albert Goldman. He mentioned it all the time in the Revelations book.
Lamar admitted that fans weren't pleased with his involvement with Goldman. He rationalized that by saying that he (Lamar) needed the money. Then he couched it further and said that Elvis didn't leave any money for him in the will.
I don't know about Lamar...throughout the book, he makes it sound like Elvis copied him. Lamar mentions that Elvis got the "my boy" saying because Lamar was doing an imitation of WC Fields, and that Elvis even took the sunglasses he was wearing to make it his (Elvis') own.
Lamar doesn't really come across as a very likeable person ! I don't know why Elvis was so loyal to him!