what is the correct way to add block as a child of an another block in xml in magento? - magento

Question

I have two custom magento blocks called "exe2" and "example".
The exe2 block gets the contents of the example block using the getChildHtml function, but it keeps just returning empty strings to me and only the exe2 contents make it to the screen.
Here is my code my code:
exe2 xml file:
<layout version = "0.1.0">
<test_example_view>
<block type = "exemplum_mod2/exe2" name = "exemplum.mod2.exe2" template="exemplum/mod2/exe2.phtml">
<reference name = "exemplum.mod2.exe2">
<block type="exemplum/example" name="exemplum.example" template="exemplum/example1/example.phtml" />
</reference>
</block>
</test_example_view>
example xml file
<layout version="0.1.0">
<default>
<block type="exemplum/example" name="exemplum.example" template="exemplum/example1/example.phtml" />
</default>
Here is the exe2 phtml file that has the getChildHtml call in it:
<h1> 2nd </h1>
<?php
echo $this->getMessage();
echo $this->getChildHtml("exemplum.mod2.exe2");
?>
hello
example.phtml file:
<h1>Hello there</h1>
And finally heres the controller file that loads the blocks:
<?php
class exemplum_example1_ExampleController extends Mage_Core_Controller_Front_Action{
public function viewAction(){
$this->loadLayout();
$block = $this->getLayout()->createBlock('exemplum_mod2/exe2');
$block->setTemplate("exemplum/mod2/exe2.phtml");
$this->getLayout()->getBlock('content')->append($block);
$this->renderLayout();
}
}
What is the correct way to add one block as the child block of a another block in the xml file? Every solution that i found on google didn't seem to work in my case so what am i doing wrong here?