Checking the search for multisite table prefix, http://drupal.org/search/node/multisite+table+prefix, you can find a few examples.
 
Specifically see this page,http://drupal.org/node/22267. I believe you will need to reverse your thinking and make the default -> 'site1', and then list all the shared tables.
 
Greg
From: support-bounces@drupal.org [mailto:support-bounces@drupal.org] On Behalf Of VJ Rao
Sent: Tuesday, August 29, 2006 10:02 AM
To: support@drupal.org; development@drupal.org
Subject: [support] Re: multisite

I am using 4.7.3 btw. I understand this means I have to share the menu table (for different primary links). Anything else?
 
Regards,
 
V

 
On 8/28/06, VJ Rao <cmsconsultant@gmail.com> wrote:
Hi,
 
If I want to share users and data across multiple sites (If there is any need for control, I plan to use TAC) ..which tables should I create as unique for each website (i.e with prefix)?
 
I can think of 'variable' . Does any other table need a prefix?
 
If not, I can just do :
 
$db_prefix = array(
      'default'   => '',
      'variable' => 'site1_'
);
in sites/site1/settings.php..
right?
 
 
 
Regards,
 
V
 
p.s I dont use left navigation