>I have a form class that accepts 2 parameters in the Init method. I have subclassed the original class and extended it's functionality. I want the sub-classed form to have a 3rd param. How can I accept another param without rewriting the whole init method in the second class?

When you subclass the form, it should automatically add your parameters to the Event:

LPARAMETERS teParam1, teParam2

Add another parameter to that list, and depending on where want your parent class code to run in relation to your new code, call DoDefaut(teParam1, teParam2)