Though my name is not as common as Kennedy or Murphy, it is one of those fortunate names that ends in a "y." (Notice the correct punctuation with a quotation mark so you can take me seriously.) I wouldn't cause much of a fuss, but still would feel a little insulted if the "y" in my last name was replaced entirely by an "ies." Regardless of the rules, I prefer the "ys" for pluralization.

Plus, I work in the legal field and have a BA in English. I agree with "Anonymous 2" that commonly-accepted writing should control. Language is constantly adapting and changing and to try to force the rules down another's throat is counter-intuitive to remaining current and relevant (the word "ask" was originally "aks" and some today are reverting, by common use, to the old pronunciation and spelling.)

When writing names in the legal field it is especially important to refer to someone with the exact spelling of their name or the opposing counsel can make an argument that you are creating confusion for the court (whether a judge agrees, the other side can still argue it and make you look stupid.)