http://forum.virtuemart.net/index.php?topic=101625.0 (http://forum.virtuemart.net/index.php?topic=101625.0)
http://forum.virtuemart.net/index.php?topic=101586.0 (http://forum.virtuemart.net/index.php?topic=101586.0)
Please, explore these topics and include solutions into the source code.