Show parents at first level then child in each page So I made a view and attached it to head of another view, what I want is at the second view page only shows the parent, but when a user click on the parent term, it now show the child terms of that parent.

Parent 1
--Child 1
--Child 2
Parent 2
--Child 3
--Child 4


For instance if anyone click on parent 1, now the view that is attched show Child 1 &amp; Child 2

I found a similar question here but no answer there.
If I am understanding your requirement correctly, you want to display "Parent Term" in top of the view page and when user click on any "Parent term", you want to display child of that term in the same page.

I have created a views and add attachment to display "Parent term" in top of the page. I have added "Taxonomy Vocabulary" filter, so please change filter in views as per your requirement.

Exported version of the view:

$view = new view();
$view-&gt;name = 'test_category';
$view-&gt;description = '';
$view-&gt;tag = 'default';
$view-&gt;base_table = 'taxonomy_term_data';
$view-&gt;human_name = 'Test Category';
$view-&gt;core = 7;
$view-&gt;api_version = '3.0';
$view-&gt;disabled = FALSE; /* Edit this to true to make a default view disabled initially */

/* Display: Master */
$handler = $view-&gt;new_display('default', 'Master', 'default');
$handler-&gt;display-&gt;display_options['title'] = 'Test Category';
$handler-&gt;display-&gt;display_options['use_more_always'] = FALSE;
$handler-&gt;display-&gt;display_options['access']['type'] = 'perm';
$handler-&gt;display-&gt;display_options['cache']['type'] = 'none';
$handler-&gt;display-&gt;display_options['query']['type'] = 'views_query';
$handler-&gt;display-&gt;display_options['exposed_form']['type'] = 'basic';
$handler-&gt;display-&gt;display_options['pager']['type'] = 'full';
$handler-&gt;display-&gt;display_options['pager']['options']['items_per_page'] = '10';
$handler-&gt;display-&gt;display_options['style_plugin'] = 'default';
$handler-&gt;display-&gt;display_options['row_plugin'] = 'fields';
/* Relationship: Taxonomy term: Parent term */
$handler-&gt;display-&gt;display_options['relationships']['parent']['id'] = 'parent';
$handler-&gt;display-&gt;display_options['relationships']['parent']['table'] = 'taxonomy_term_hierarchy';
$handler-&gt;display-&gt;display_options['relationships']['parent']['field'] = 'parent';
/* Field: Taxonomy term: Name */
$handler-&gt;display-&gt;display_options['fields']['name']['id'] = 'name';
$handler-&gt;display-&gt;display_options['fields']['name']['table'] = 'taxonomy_term_data';
$handler-&gt;display-&gt;display_options['fields']['name']['field'] = 'name';
$handler-&gt;display-&gt;display_options['fields']['name']['label'] = '';
$handler-&gt;display-&gt;display_options['fields']['name']['alter']['word_boundary'] = FALSE;
$handler-&gt;display-&gt;display_options['fields']['name']['alter']['ellipsis'] = FALSE;
$handler-&gt;display-&gt;display_options['fields']['name']['element_label_colon'] = FALSE;
$handler-&gt;display-&gt;display_options['fields']['name']['link_to_taxonomy'] = TRUE;
/* Contextual filter: Taxonomy term: Parent term */
$handler-&gt;display-&gt;display_options['arguments']['parent']['id'] = 'parent';
$handler-&gt;display-&gt;display_options['arguments']['parent']['table'] = 'taxonomy_term_hierarchy';
$handler-&gt;display-&gt;display_options['arguments']['parent']['field'] = 'parent';
$handler-&gt;display-&gt;display_options['arguments']['parent']['default_action'] = 'empty';
$handler-&gt;display-&gt;display_options['arguments']['parent']['default_argument_type'] = 'taxonomy_tid';
$handler-&gt;display-&gt;display_options['arguments']['parent']['default_argument_options']['node'] = TRUE;
$handler-&gt;display-&gt;display_options['arguments']['parent']['default_argument_options']['vocabularies'] = array(
  'product_category' =&gt; 'product_category',
);
$handler-&gt;display-&gt;display_options['arguments']['parent']['summary']['number_of_records'] = '0';
$handler-&gt;display-&gt;display_options['arguments']['parent']['summary']['format'] = 'default_summary';
$handler-&gt;display-&gt;display_options['arguments']['parent']['summary_options']['items_per_page'] = '25';
/* Filter criterion: Taxonomy term: Vocabulary */
$handler-&gt;display-&gt;display_options['filters']['vid']['id'] = 'vid';
$handler-&gt;display-&gt;display_options['filters']['vid']['table'] = 'taxonomy_term_data';
$handler-&gt;display-&gt;display_options['filters']['vid']['field'] = 'vid';
$handler-&gt;display-&gt;display_options['filters']['vid']['value'] = array(
  3 =&gt; '3',
);
/* Filter criterion: Taxonomy term: Term ID */
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['id'] = 'tid_raw';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['table'] = 'taxonomy_term_data';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['field'] = 'tid_raw';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['relationship'] = 'parent';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['operator'] = 'not empty';

/* Display: Page */
$handler = $view-&gt;new_display('page', 'Page', 'page');
$handler-&gt;display-&gt;display_options['path'] = 'test-category';

/* Display: Attachment */
$handler = $view-&gt;new_display('attachment', 'Attachment', 'attachment_1');
$handler-&gt;display-&gt;display_options['pager']['type'] = 'some';
$handler-&gt;display-&gt;display_options['defaults']['arguments'] = FALSE;
/* Contextual filter: Taxonomy term: Term ID */
$handler-&gt;display-&gt;display_options['arguments']['tid']['id'] = 'tid';
$handler-&gt;display-&gt;display_options['arguments']['tid']['table'] = 'taxonomy_term_data';
$handler-&gt;display-&gt;display_options['arguments']['tid']['field'] = 'tid';
$handler-&gt;display-&gt;display_options['arguments']['tid']['default_action'] = 'summary';
$handler-&gt;display-&gt;display_options['arguments']['tid']['default_argument_type'] = 'fixed';
$handler-&gt;display-&gt;display_options['arguments']['tid']['summary']['number_of_records'] = '0';
$handler-&gt;display-&gt;display_options['arguments']['tid']['summary']['format'] = 'default_summary';
$handler-&gt;display-&gt;display_options['arguments']['tid']['summary_options']['count'] = FALSE;
$handler-&gt;display-&gt;display_options['arguments']['tid']['summary_options']['items_per_page'] = '25';
$handler-&gt;display-&gt;display_options['arguments']['tid']['specify_validation'] = TRUE;
$handler-&gt;display-&gt;display_options['arguments']['tid']['validate']['fail'] = 'summary';
$handler-&gt;display-&gt;display_options['defaults']['filter_groups'] = FALSE;
$handler-&gt;display-&gt;display_options['defaults']['filters'] = FALSE;
/* Filter criterion: Taxonomy term: Vocabulary */
$handler-&gt;display-&gt;display_options['filters']['vid']['id'] = 'vid';
$handler-&gt;display-&gt;display_options['filters']['vid']['table'] = 'taxonomy_term_data';
$handler-&gt;display-&gt;display_options['filters']['vid']['field'] = 'vid';
$handler-&gt;display-&gt;display_options['filters']['vid']['value'] = array(
  3 =&gt; '3',
);
/* Filter criterion: Taxonomy term: Term ID */
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['id'] = 'tid_raw';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['table'] = 'taxonomy_term_data';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['field'] = 'tid_raw';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['relationship'] = 'parent';
$handler-&gt;display-&gt;display_options['filters']['tid_raw']['operator'] = 'empty';
$handler-&gt;display-&gt;display_options['displays'] = array(
  'page' =&gt; 'page',
  'default' =&gt; 0,
);
$handler-&gt;display-&gt;display_options['inherit_arguments'] = FALSE;