But you may wish to consider:
A crowd was sitting around Him, and they said to Him, "Behold, Your mother and Your brothers are outside looking for You." Answering them, He said, "Who are My mother and My brothers?" Looking about at those who were sitting around Him, He said, "Behold My mother and My brothers! For whoever does the will of God, he is My brother and sister and mother." Mark 3:32-35
If brothers are cousins what are "sisters"?
What does the original Greek say?
Harley, come on... you're pulling a sleight of hand.
But unlike in English, "cousin" can take on a feminine form. So your answer is that "sister" is "adelpha." But you'll notice I did address the condition problemmatic for the Catholic argument that it is unusual for "adelphae" and "adelphi*" to be addressed separately in the same sentence. Were it not for this peculiarity, there would never be any evidence at all that James et al referred to Jesus' brothers and not his cousins. Since there is this peculiarity, it was needed to create an argument to demonstrate that James was in fact a cousin, and not a brother.
(* As I am presently away from my resources, I'm not positive if that is the correct plural of "adelphos.")
Wanna ping the horde?
By the way, I saw on another thread, by bizarre coincidence the assertion that Mary of Clopas was not a sister-in-law, but in fact a sister! The discussion was about Mary Magdeleine, and the assertion was made that Mary Magdeliene was sister to Mary, Martha and Lazarus of Bethany. The author asserted that there had been Jewish prophecies shortly before Christ that the Messiah was about to be born to a woman named Mary. As a result, it was not unheard of for believers in this prophecy to name each daughter Mary. This wouldn't affect my theory at all. The bigger problem is that it's hard to picture St. Anne having other children, given the Catholic legends surrounding her.