Possible Duplicate:
Is “my wife and I's” correct, or should it be “my wife's and my”?
Preferred way to apostrophise in case of dual or multiple ownership by distinct entities?
What is the correct grammar to use in a phrase like "Chris' and Claire's email addresses"? Is it correct to add the apostrophe to each owner in the list?
I think I will start using the "Chris's" form based on the couple of questions here: http://english.stackexchange.com/questions/1073/what-is-the-correct-possessive-for-nouns-ending-in-s http://english.stackexchange.com/questions/2964/when-did-it-become-correct-to-add-an-s-to-a-singular-possessive-already-ending
– Andrew Moss Sep 05 '11 at 12:31