diff --git a/core/modules/migrate/src/Entity/Migration.php b/core/modules/migrate/src/Entity/Migration.php
index ba563f1..78a0605 100644
--- a/core/modules/migrate/src/Entity/Migration.php
+++ b/core/modules/migrate/src/Entity/Migration.php
@@ -14,6 +14,7 @@
 use Drupal\migrate\MigrateSkipRowException;
 use Drupal\migrate\Plugin\MigrateIdMapInterface;
 use Drupal\migrate\Plugin\RequirementsInterface;
+use Drupal\Component\Utility\NestedArray;
 
 /**
  * Defines the Migration entity.
@@ -406,6 +407,29 @@ public function setProcess(array $process) {
   /**
    * {@inheritdoc}
    */
+  public function setProcessOfProperty($field_name, $process) {
+    $this->process[$field_name] = $process;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function mergeProcessOfProperty($field_name, array $process) {
+    // If we already have a process value then merge the incoming process array
+    //otherwise simply set it.
+    if (isset($this->process[$field_name])) {
+      $this->process = NestedArray::mergeDeepArray([$this->process, [$field_name => $process]], TRUE);
+    }
+    else {
+      $this->setProcessOfProperty($field_name, $process);
+    }
+
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function getSystemOfRecord() {
     return $this->systemOfRecord;
   }
diff --git a/core/modules/migrate/src/Entity/MigrationInterface.php b/core/modules/migrate/src/Entity/MigrationInterface.php
index 09cc770..fc575a2 100644
--- a/core/modules/migrate/src/Entity/MigrationInterface.php
+++ b/core/modules/migrate/src/Entity/MigrationInterface.php
@@ -198,6 +198,36 @@ public function getProcess();
   public function setProcess(array $process);
 
   /**
+   * Set the process for an individual destination field.
+   *
+   * @param string $field_name
+   *   The field name of which to set the process.
+   * @param mixed $process
+   *   A valid process value, array or string.
+   *
+   * @return $this
+   *   The migration entity.
+   *
+   * @see Drupal\migrate_drupal\Plugin\migrate\load\LoadEntity::processLinkField().
+   */
+  public function setProcessOfProperty($field_name, $process);
+
+  /**
+   * Merge the process arrays for an individual field.
+   *
+   * @param string $field_name
+   *   The field name of which to set the process.
+   * @param array $process
+   *   An array of process data.
+   *
+   * @return $this
+   *   The migration entity.
+   *
+   * @see Drupal\migrate_drupal\Plugin\migrate\load\LoadEntity::processLinkField().
+   */
+  public function mergeProcessOfProperty($field_name, array $process);
+
+  /**
    * Get the current system of record of the migration.
    *
    * @return string
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/load/LoadEntity.php b/core/modules/migrate_drupal/src/Plugin/migrate/load/LoadEntity.php
index c9db0e7..f04672d 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/load/LoadEntity.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/load/LoadEntity.php
@@ -98,9 +98,7 @@ public function loadMultiple(EntityStorageInterface $storage, array $sub_ids = N
                 $this->processTextField($field_name, $data, $migration);
                 break;
               default:
-                $process = $migration->getProcess();
-                $process[$field_name] = $field_name;
-                $migration->setProcess($process);
+                $migration->setProcessOfProperty($field_name, $field_name);
             }
           }
         }
@@ -134,12 +132,11 @@ protected function processTextField($field_name, $field_data, MigrationInterface
     $value_key = $field_data['db_storage'] ? $field_name : "$field_name/value";
     $format_key = $field_data['db_storage'] ? $field_name . '_format' : "$field_name/format" ;
 
-    $process = $migration->getProcess();
+    $migration->setProcessOfProperty("$field_name/value", $value_key);
 
-    $process["$field_name/value"] = $value_key;
     // See d6_user, signature_format for an example of the YAML that
     // represents this process array.
-    $process["$field_name/format"] = [
+    $process = [
       [
         'plugin' => 'static_map',
         'bypass' => TRUE,
@@ -153,8 +150,7 @@ protected function processTextField($field_name, $field_data, MigrationInterface
         'source' => $format_key,
       ],
     ];
-
-    $migration->setProcess($process);
+    $migration->mergeProcessOfProperty("$field_name/format", $process);
   }
 
   /**
@@ -168,8 +164,7 @@ protected function processTextField($field_name, $field_data, MigrationInterface
    *   The migration entity.
    */
   protected function processFileField($field_name, $field_data, MigrationInterface $migration) {
-    $process = $migration->getProcess();
-    $process[$field_name] = [
+    $process = [
       'plugin' => 'd6_cck_file',
       'source' => [
         $field_name,
@@ -177,7 +172,7 @@ protected function processFileField($field_name, $field_data, MigrationInterface
         $field_name . '_data',
       ],
     ];
-    $migration->setProcess($process);
+    $migration->mergeProcessOfProperty($field_name, $process);
   }
 
   /**
@@ -193,8 +188,7 @@ protected function processFileField($field_name, $field_data, MigrationInterface
   protected function processLinkField($field_name, $field_data, MigrationInterface $migration) {
     // Specifically process the link field until core is fixed.
     // @see https://www.drupal.org/node/2235457
-    $process = $migration->getProcess();
-    $process[$field_name] = [
+    $process = [
       'plugin' => 'd6_cck_link',
       'source' => [
         $field_name,
@@ -202,7 +196,7 @@ protected function processLinkField($field_name, $field_data, MigrationInterface
         $field_name . '_attributes',
       ],
     ];
-    $migration->setProcess($process);
+    $migration->mergeProcessOfProperty($field_name, $process);
   }
 
 }