Change Revisions to By Project late in the game?

I know you are supposed to make a decision on this early, and most of our users know this ;) But we have one project that was set up for Revision By Sheet, and a first round of revisions have been done, and now the Project Architect wants to change it. Is there any easy answer, or do they need to delete all the revisions, change to By Project, then start revisions again?

Thanks,
Gordon

No easy way unfortunately. It would be nice if we could change on the fly to do revision on 150 sheets then back to individual.
Do you need to reset all the revision ?