Neil,

> many thanks for your answer. Thinking about it, it sounds horrendously complicated. I can see I'm going to have to consider the "Why Bother" factor very seriously indeed.

I wouldn't use the words "horrendously complicated", but you do have to rethink design and information flow for distributed or web applications. Generally, you'll probably be able to find ways to gather more info at one time from the user before hitting the backend again, instead of lots of little steps with user responses between.

But, sometimes you can't avoid multi-step requirements, and must use some kind of state-keeping method.