Hi,
I would strongly suggest you try running the form I sent you earlier and see if it works for you. The form I designed is actually meant to answer your question as you explain. Try deploying that form and testing using collect application and see if it does not sort you out.
Your logic can be summarized as Q2 will only appear when Q1 has failed. So it means either Q1 or Q2 can be answered but priority should be to Q1 over Q2.
Stephane
