I had a brainwave, but if you could verify it would work and help with syntax, that would be useful.
I think I can work around my problem if I have two update behaviours on same page.
If I can 'trigger' the update behaviours using a session value (for example, sessionBillingEmpty=true/false) I can remove the bindings on one of the updates, so a blank is not put in.
Question is, can I trigger the update behaviour based on a session value?
Thanks,
Ben