Can two xmark users add and edit bookmarks in the same folder?

Hi. I read about share folders. It sounds like that I can share a folder and then push it as a RSS feed. But is it not possible truely to share a folder so two xmark users both can add and edit bookmarks in 1-2 folders but still keep the rest of ones bookmarks personal? That would be a really usefull feature if not allready there.

Br. Anders