exchange-2010 – How to Configure a ‘Catchall Account’ in Exchange 2010

My first question is are the affected users members of (or have ever been a member of) a privileged group (such as Domain Admins or Enterprise Admins)? If so, ActiveSync has issues with administrative accounts.

You can turn up the diagnostic logging for ActiveSync to hopefully give you some pointers to the problem. Open up the Exchange Management Console and go to Server Configuration => Mailbox and chose Manage Diagnostic Logging Properties from the action pane.

Turn the MSExchange-ActiveSync options up to High and try to sync your iPhone and see if you get anything useful. Be sure to change the logging back down to Lowest when you've done - your server will love you for it.

This is not possible. BES stores hidden device information such as PIN in your mailbox, activating a second blackberry will override the hidden information from the first device.

Your only options would be to setup desktop syncing, in which the devices would sync, but not wirelessly. Alternatively you could go with less features and sync via smtp, or use mailbox forwarding to sync inbound messages between the groups. Unfortunately this will not give the features you describe in your question.