Upgrading concerns - RH5 to RH7 Modular Project

I'm updating the online help our company offers to customers. The existing help is modular, with about 20 separate help projects representing different modules or aspects of our software product. Each of these projects is a book in the combined Table of Contents (which is what customers see).

We expect to buy RH7 next month, meanwhile, I'm demonstrating how I would use the new RoboHelp. In particular, I'm adding Bread Crumb trails and an Index, while improving the navigation/reducing the number of clicks to get the answer.

My management wants me to release new topics one at a time.

Will the new projects work with the old ones? If I select the old path when executing the publish command, this should put the new material in place of the old. But will the new features--Bread Crumb trails and the Index work in an old combined project? If only one of the modules has breadcrumbs and an index, will the combined project work correctly?

Thanks for any suggestions.

I do not want to attach any materials. My management is very strict about not releasing such things.