Capturing POST data

It points to options.php because it uses the Settings API. Well, not completely, but that’s not the point now. You should not change that.

What you can do, to add your own logic: hook into the save process for that option:

add_filter( "sanitize_option_webweb-member-status-group", "your_extra_handler" );

function your_extra_handler( $input )
{
    if ( isset ( $_POST['your_extra_post_field'] ) )
        // do something awesome

    return $input; // don’t touch that value
}