[Jean le Chauve]

Regarde le module CGSimpleSmarty, il y a ce que tu veux :
get_parent_alias([$alias],[$assign])
Returns the alias of the specified pages parent. Returns an empty string if there is no parent.
Arguments:
[$alias] - (optional) The page alias to find the parent of. If no value is specified, the current page is used.
[$assign] - (optional) The name of a variable to assign the results to.

Example:
The parent page alias is {$cgsimple->get_parent_alias()}