I'm designing for an app that helps companies generate complex legal documents.
We generally use a wizard with progress noted at the top. The progress can branch quite dramatically. We're faced with a problem where users realize they should have selected another option earlier, so use the wizard to return to the step they need to change - and enter different information. It could be that the information doesn't change anything else, it could be that it renders another step down the line invalid, it could be that it completely changes the path of their wizard.
We're reusing the same framework for dozens if not hundreds of legal processes so we need a UI that works repeatedly.
Where should we tell the user that they are about to over-write everything past this point? When they start entering information into a field on the older page? When they are about to submit conflicting information?
Does anyone have any advice for these types of complex branching wizards where a user might jump back in the progress?