Проверено в smarty: Добавить 1 день, 2 дня ...... 365 дней в динамической дате.
$one= date("Y-m-d", strtotime(date("Y-m-d", strtotime('$add dynamic date variable')) . " + 1 day"));
$this->smarty->assign('one',$one);
$two= date("Y-m-d", strtotime(date("Y-m-d", strtotime('$add dynamic date variable')) . " + 2 day"));
$this->smarty->assign('two',$two);
...
..
$oneyear= date("Y-m-d", strtotime(date("Y-m-d", strtotime('$add dynamic date variable')) . " + 365 day"));
$this->smarty->assign('oneyear',$oneyear);