Is it possible to override a SilkTest function?
No. There is no way that the built-in functions of SilkTest can be overridden. Although it is possible to overide methods and properties of user created and standard classes there is no way it can be done for a function as they do not depend on an actual object when being invoked.
The best way to work around this is to create a new function which can either call the original function and carry out any additional processing or create a completely new function. The only stipulation is that it must not use the name of the original function.