Wardrobe Wizard is a utility that will take a clothing model created to fit one figure and convert it to fit another. It has been included in Poser since version 8. Prior to that is was available separately.

http://www.philc.net/WW2_help.php plus there is a full chapter on it in the Poser manual.

Accessed via the Poser menu Scripts > Wardrobe Wizard Menu.

Hope that helps.