So, why not create two web browsers? If you have one that you want to use in an automated fashion from form4, and another that you want the user to be able to use directly from Form1, then why not have two different ones? It kind of sounds like you may not even need to see one of them.

On the other hand, if you want the resuls to be visible to the user in either case, then using one is probably the right way to go. Technically, you could use two and just show one or the other, but that seems wasteful. If you don't want anything running after completion in some cases, then pass a Boolean to form1. Only run the code in the DocumentCompleted handler if the Boolean is true.