two accounts in one interface

[aviriel]

Dear all
I have a crazy idea and I don't know how to realize it. Can you help me with this?
Lets imagine that we have two accounts: a@example.com (A) and b@example.net (B). Both of them are Zimbra accounts from the one server. Both of them have one owner.
Question: can I merge this accounts to one? I need to merge not only mail, but everything: calendars, documents, tasks and so on. One more requirement: I need to have a possibility to divide them again later.
For example, I open web-interface of Zimbra with my credentials from one the accounts and see the single inbox. I open the calendar tab and see two enabled calendars. I open my tasks and see all tasks from accounts A and B. But if I want to give account B to my friend and leave only account A for myself then I can divide B back from A. After this I need to use only account A with all the data, that have been received to it. And all the mail, tasks and calendars from account B should go away with account B.

Is it possible? If there is no standard feature that can help me then do you have any ideas how can I add such functionality?

[phoenix]

How about using the Share function to share the components (mailbox, calendar, briefcase) with another user? Have a look at the Admin Guide (or the Web UI online help) for further details.

[aviriel]

But can I answer from account B to mails? I know how to add external accounts and aliases and give an answer from aliases. But how can I answer from account B if I open the web-interface from A and have a shared Inbox folder? It is a main question.
The same questions with tasks. Can I open in one interface all task lists or should I use them separately?
One more problem:
If I share the briefcase, I can't use some of the documents after the separation of accounts. It means that I need to add new documents only after the login to the right account.