How to display all children on parent node for custom content type? I have a custom content type, let's call it 'parent'. I have another custom content type, let's call it 'child'. 

I created a template file where I can display the 'parent' content type fields any way I want: node--parent.tpl.php. By using code such as...

&lt;?php
  print $content['field_city'][0]['#markup'];
?&gt;


I can move fields around and customize the markup, which is great. But how would I also display the parent's children on the same page?

(I don't use Views. I create a content type template file instead because gives me more flexibility for arranging the HTML).
How are the children linked to the parent? Do you use an Entity Reference field?

Also, what do you want to display from the children? The titles? The entire, rendered nodes?

If you look up entity_metadata_wrapper (see: Entity metadata wrappers) you can see how to access an Entity Reference field.

You also may want to reconsider Views. Overriding templates for Views can give you a lot of flexibility.