>I have accidently created an object (in fact a form based on my own form class)using the correct class but from the wrong class library (actually from a backup of the class on another disk). Can I edit the form class so it uses the correct class library?

Yo can download a VFP hacking tool at http://www.visionds.com/VMPSite/VFP/default.asp. It "allows you (among other things), to redefine the Parent of existing forms/classes and their members".