Priscilla Presley, regularly answers the questions of Elvis fans via her Facebook page.
Here is a fan question regarding Lisa's name and Priscilla's answer from July 10th.
Q: How did you and Elvis choose Lisa Marie's name?
A: "I bought a book of baby names for Elvis and I to choose from. We would lay in bed night after night looking through all the names that would sound good together. We decided that Lisa Marie was beautiful for a girl and I loved the name John Baron for a boy...he agreed. From what I hear, it was written somewhere that we may have taken the name Marie after Col. Parker, his manager's wife, who was named Marie. That is not true. We just simply... liked those two names together."