I think things are changing with time. Now we have to pay $335 per person to St. Louis instead of $265. And this could be true for the passport ammendment too.
So contact your local consulate and get it done to be on the safe side.
It just cost $10 and a weeks time. I have spoken to Chicago Consulate and they told me to fill out the Miscellenous section of the form for this. Make sure to call them before sending anything. Because in my case, My wifes name does not change, only my name needs to be put on her passport on the spouse section.
GoodLuck.