add_filter ( 'woogc/ps/interfaces/synchronize_to_sites', 'woogc_ps_interfaces_synchronize_to_sites' );
    function woogc_ps_interfaces_synchronize_to_sites( $sites )
         {

             $keep_shops    =   array ( 2, 3, 5 );

             foreach ( $sites    as  $key    =>  $site )
                 {
                     if ( ! in_array ( $site->blog_id, $keep_shops ) )
                         unset ( $sites[ $key ] );
                 }

             return $sites;
         }