>I am starting a small project using the application builder. The purpose will be to extract a customer's data from several Foxpro 2.6 tables into my VFP 6.0 application for viewing and editing.
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>Should I use the Foudation Classes setup by VFP or should I setup my own copy of all of the VFP Base Classes?
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>What if I want to change one of those Foundation Classes for my own use? How do I get back to the original if needed?

You should subclass the Foundation Classes if you use them rather than changing any of them.