I have two different accounts I need to access on a regular basis. This is easy on Windows, but to switch between the two accounts on Android, I have to sign out of one, then sign in to the other. However, sign out removes all cached notes and offline notebooks. My two accounts have 9,000 [2.5 GB] and 7,000 [3.5 GB] notes, respectively. Even with a fast connection, the time to resync that much data on an account switch takes far too long to make this usable. In addition, there are other problems. Sharing isn't too bad when dealing with just a few notebooks and tags. However, there are serious deficiencies when more data and structure enters the picture. My two accounts have completely different attributes, each with a couple dozen stacks, dozens of notebooks, thousands of notes, and hundreds of tags, all with hierarchical structure. I've been experimenting with shared notebooks, using about 4,000 notes, and have observed the following. 1) All notebook and tag structure is lost by sharing. This in turn totally disrupts the structure of the account to which the notebooks are shared. Tags, especially, become unmanageable. Windows carries forward the tags from a joined notebook, but Android does not. Tag search becomes impossible for Android, as there are none, and difficult for Windows because of the lack of structure. The tag hierarchy cannot even be reproduced as Evernote for Windows does not permit the tags from joined notebooks to be repositioned. Although Android does separate out joined notebooks from the others, though still losing the structure of stacks, Windows does not, and the shared notebooks are co-mingled within the existing structure. 2) Since sharing transcends platforms, i.e., I cannot share for Android only, as it really isn't needed for Windows, all shared notebook content is physically added to the Windows database, effectively doubling the database size. This elongates synchronisation times and search times. 3) Of course, every time a new notebook is created in the account that shares the notebooks, it must be newly shared. Then, each Android device needs to set the notebook attribute to offline sync. All of these problems are not unique to using Android. The loss of hierarchical structure for notebooks and tags still causes significant problems for the Windows platform. I suspect this problem has not been generally understood, and therefore ignored. Perhaps, if other users would comment on this thread, the subject would get more attention, and thus get addressed. I have only looked at the implications regarding Windows and Android platforms, but other supported platforms may present similar problems. There may also be issues with regard to using the Evernote Business offering. Oh, the ticket is # 536445.