Thanks, Bruce
Ultimately, I used your suggestion but it wasn't the simple solution I hoped existed. The switch condition as well as numerous session values used by both the Source Form and the Target Form were all generated in the Source Form. So these had to be rewritten as separate procedures that could be called from the Web handler and both forms. Not particularly difficult, but time consuming.
I am surprised this situation hasn't come up more often. Ie., user wants to do something normally done with procedure A, but some condition fails, so send them to procedure B. An internal redirect that can be called from most of an NT procedure. If it isn't a big job, it would be a nice function.
Thanks again.