I use Outlook, but I assume it is the same in OE. You can make a new folder for each member of your family, and give them different names (John, Betty,etc) Then make a rule to send emails from different addresses (Each of Johns Friends for example)to the new folders. This would only work with each ones personal friends, but any others would go to your in box. At least it would keep personal emails apart.
I hope this helps although not a complete solution to your problem.