How do you change your synced/shared Endnote X8 library?

I understand that with Endnote X8, you can only share one library wtih multiple people.  Once the project is completed and I want to share a new lirary, how can replace the current synced library with a new one (not merge them)?

Will there be a future development in Endnote where someone can share mutiple libraries? For example, I am lead author on 2 separate journal articles on very different topics with a completely different set of co-authors. Is there a way I can share each library with co-authors without having to create multiple accounts? 

Thanks

You can group the references for each subject  in one library, which is what I do.  Then you can share different groups with your different coauthors from endnote online.  Even though I have different subjects, there is always some overlap (technologies, overarching reviews, etc) and thus I have always maintained one library.  Like since the 1990s or maybe earlier!