diff --git a/embargo.install b/embargo.install
new file mode 100644
index 0000000..bb5dda8
--- /dev/null
+++ b/embargo.install
@@ -0,0 +1,39 @@
+<?php
+
+/**
+ * @file
+ * Install file.
+ */
+
+use Drupal\Core\Field\BaseFieldDefinition;
+use Drupal\Core\Utility\UpdateException;
+
+/**
+ * Add a new field to the existing Embargo entity type.
+ */
+function embargo_update_8001() {
+  $entity_type_id = 'embargo';
+  $bundle = 'embargo';
+
+  $definition_manager = \Drupal::entityDefinitionUpdateManager();
+
+  try {
+    // Create a new field definition.
+    $new_field = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Embargoed File'))
+      ->setDescription(t('New field for attaching media to the Embargo node.'))
+      ->setSetting('target_type', 'media')
+      ->setCardinality(BaseFieldDefinition::CARDINALITY_UNLIMITED);
+
+    // Install the new definition.
+    $definition_manager->installFieldStorageDefinition('embargoed_file', $entity_type_id, $bundle, $new_field);
+  }
+  catch (UpdateException $e) {
+    // Handle exception if needed.
+    \Drupal::logger('embargo')->error('Error adding field: @error', ['@error' => $e->getMessage()]);
+    return t('Update failed: @error', ['@error' => $e->getMessage()]);
+  }
+
+  // Provide a message indicating the update has been applied.
+  return t('Added embargoed_file to the Embargo entity.');
+}
diff --git a/embargo.libraries.yml b/embargo.libraries.yml
new file mode 100644
index 0000000..3aff315
--- /dev/null
+++ b/embargo.libraries.yml
@@ -0,0 +1,7 @@
+custom_select_all_library:
+  version: 1.x
+  js:
+    js/custom_select_all.js: {}
+  dependencies:
+    - core/jquery
+    - core/once
diff --git a/embargo.module b/embargo.module
index c5b35dc..881f49a 100644
--- a/embargo.module
+++ b/embargo.module
@@ -9,6 +9,8 @@ use Drupal\Core\Database\Query\AlterableInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\embargo\EmbargoStorage;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\node\NodeInterface;
 
 /**
  * Implements hook_entity_type_alter().
@@ -97,3 +99,69 @@ function embargo_theme($existing, $type, $theme, $path) {
     ],
   ];
 }
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function embargo_form_alter(&$form, FormStateInterface $form_state, $form_id) {
+  if ($form_id == 'embargo_add_form' || $form_id == 'embargo_edit_form') {
+    // Set up visibility conditions for the embargoed_file field.
+    $form['embargoed_file']['#states'] = [
+      'visible' => [
+        ':input[name="embargo_type"]' => ['value' => 0],
+      ],
+    ];
+
+    // Check if the URL contains a node ID.
+    $node_id = \Drupal::routeMatch()->getParameter('node');
+
+    if ($node_id instanceof NodeInterface) {
+      $node_id = $node_id->id();
+    }
+
+    // If its edit form, need to select node id differently.
+    if ($form_id == 'embargo_edit_form') {
+      $entity = $form_state->getFormObject()->getEntity();
+      $field_value = $entity->embargoed_node->getValue();
+      $node_id = $field_value[0]['target_id'];
+    }
+
+    // If a node ID is present, filter the options of embargoed_file.
+    if (!empty($node_id)) {
+      $options = embargo_get_filtered_file_options($node_id);
+      $form['embargoed_file']['widget']['#options'] = $options;
+    }
+    else {
+      // @todo Need to update file list via ajax when Embargoed Node available.
+      unset($form['embargoed_file']);
+    }
+
+    // JS to add Select/Unselect All link and functionality.
+    $form['#attached']['library'][] = 'embargo/custom_select_all_library';
+
+  }
+}
+
+/**
+ * Helper function to get filtered options based on the node ID.
+ */
+function embargo_get_filtered_file_options($node_id) {
+  // Initialize an empty array to store matching media entities.
+  $matching_media = [];
+
+  // Check if the node ID is valid.
+  if (!empty($node_id)) {
+    // Filter media entities based on the referenced node ID.
+    $matching_media = \Drupal::entityTypeManager()
+      ->getStorage('media')
+      ->loadByProperties(['field_media_of' => $node_id]);
+  }
+
+  // Build an array of matching media labels and IDs for the checkbox options.
+  $options = [];
+  foreach ($matching_media as $media) {
+    $options[$media->id()] = $media->label();
+  }
+
+  return $options;
+}
diff --git a/js/custom_select_all.js b/js/custom_select_all.js
new file mode 100644
index 0000000..3cfb4a8
--- /dev/null
+++ b/js/custom_select_all.js
@@ -0,0 +1,21 @@
+(function ($, Drupal, once) {
+  Drupal.behaviors.customSelectAll = {
+    attach: function (context, settings) {
+      // Create the link element
+      var selectAllLink = $('<a href="#" id="edit-select-unselect-all">Select/Unselect All</a>');
+
+      // Use `once()` to ensure the link is prepended only once
+      $(once('custom-select-all', '#edit-embargoed-file', context)).prepend(selectAllLink);
+
+      // Attach the click handler directly to the link element
+      selectAllLink.on('click', function (event) {
+        event.preventDefault();
+
+        var checkboxes = $(':checkbox', context); // Target checkboxes within relevant context
+
+        // Toggle checked state based on current state of the first checkbox
+        checkboxes.prop('checked', !checkboxes.first().prop('checked'));
+      });
+    }
+  };
+})(jQuery, Drupal, once);
diff --git a/src/EmbargoInterface.php b/src/EmbargoInterface.php
index 62003e2..691931f 100644
--- a/src/EmbargoInterface.php
+++ b/src/EmbargoInterface.php
@@ -249,4 +249,22 @@ public function isUserExempt(AccountInterface $user): bool;
    */
   public function ipIsExempt(string $ip): bool;
 
+  /**
+   * Gets the embargoed files.
+   *
+   * @return \Drupal\media\MediaInterface[]
+   *   An array of media entities representing the embargoed files.
+   */
+  public function getEmbargoedFiles(): array;
+
+  /**
+   * Sets the embargoed files.
+   *
+   * @param \Drupal\media\MediaInterface[] $files
+   *   An array of media entities representing the embargoed files.
+   *
+   * @return $this
+   */
+  public function setEmbargoedFiles(array $files): EmbargoInterface;
+
 }
diff --git a/src/Entity/Embargo.php b/src/Entity/Embargo.php
index 03f8b57..2376936 100644
--- a/src/Entity/Embargo.php
+++ b/src/Entity/Embargo.php
@@ -94,6 +94,27 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ])
       ->setSetting('allowed_values', static::getEmbargoTypeLabels());
 
+    $fields['embargoed_file'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Embargoed Media'))
+      ->setDescription(t('Media attached to the Embargoed node.'))
+      ->setCardinality(FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED)
+      ->setSetting('target_type', 'media')
+      ->setSetting('handler', 'default:media')
+      ->setDisplayOptions('view', [
+        'label' => 'above',
+        'type' => 'entity_reference_label',
+        'weight' => 0,
+      ])
+      ->setDisplayOptions('form', [
+        'type' => 'options_buttons',
+        'weight' => 0,
+        'settings' => [
+          'match_operator' => 'CONTAINS',
+          'size' => '60',
+          'placeholder' => '',
+        ],
+      ]);
+
     $fields['expiration_type'] = BaseFieldDefinition::create('list_integer')
       ->setLabel(t('Expiration Type'))
       ->setDescription(t('A <em>Indefinite</em> embargo is never lifted.<br/>A <em>Scheduled</em> embargo is lifted on the specified date.'))
@@ -377,6 +398,24 @@ public function setEmbargoedNode(NodeInterface $node): EmbargoInterface {
     return $this;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getEmbargoedFiles(): array {
+    /** @var \Drupal\Core\Field\EntityReferenceFieldItemListInterface $field */
+    $field = $this->get('embargoed_file');
+    $files = $field->referencedEntities();
+    return $files;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setEmbargoedFiles(array $files): EmbargoInterface {
+    $this->set('embargoed_file', $files);
+    return $this;
+  }
+
   /**
    * The maximum age for which this object may be cached.
    *