Answer to Problem 3 (part 2)

Still having difficulty? I'll give you a clue. Let's make a list of what we know about the order B -> A:

1. The order will always fail. This is because of the rule prohibiting self-dislodgement. Even if a foreign power supports the move, it will still fail.
2. The order does not cut the support being given by A.
3. The order by itself does not protect A. Any units which could protect A by supporting B -> A could just as easily support A directly.

In sum, the order B -> A does not affect A at all!

So if the order B -> A doesn't affect A, what possible use can it have? It turns out that the move can be useful precisely because it is guaranteed not to have any effect!

I think it's time for a more concrete example....