diff --git a/CRM/Contact/Import/Parser/Contact.php b/CRM/Contact/Import/Parser/Contact.php
index 8eefbf1686dc..234faa7b5be9 100644
--- a/CRM/Contact/Import/Parser/Contact.php
+++ b/CRM/Contact/Import/Parser/Contact.php
@@ -29,8 +29,6 @@ class CRM_Contact_Import_Parser_Contact extends CRM_Import_Parser {
   use CRM_Contact_Import_MetadataTrait;
 
   protected $_mapperKeys = [];
-  protected $_mapperRelated;
-  protected $_mapperRelatedContactDetails;
   protected $_relationships;
 
   /**
@@ -112,19 +110,10 @@ class CRM_Contact_Import_Parser_Contact extends CRM_Import_Parser {
    * Class constructor.
    *
    * @param array $mapperKeys
-   * @param array $mapperLocType
-   * @param array $mapperPhoneType
-   * @param array $mapperImProvider
-   * @param array $mapperRelated
-   * @param array $mapperRelatedContactType
-   * @param array $mapperRelatedContactDetails
    */
-  public function __construct(
-    $mapperKeys = [], $mapperLocType = [], $mapperPhoneType = [], $mapperImProvider = [], $mapperRelated = [], $mapperRelatedContactType = [], $mapperRelatedContactDetails = []) {
+  public function __construct($mapperKeys = []) {
     parent::__construct();
     $this->_mapperKeys = $mapperKeys;
-    $this->_mapperRelated = &$mapperRelated;
-    $this->_mapperRelatedContactDetails = &$mapperRelatedContactDetails;
   }
 
   /**
@@ -644,15 +633,6 @@ public function import($onDuplicate, &$values) {
           //format common data, CRM-4062
           $this->formatCommonData($field, $formatting, $contactFields);
 
-          //do we have enough fields to create related contact.
-          $allowToCreate = $this->checkRelatedContactFields($key, $formatting);
-
-          if (!$allowToCreate) {
-            $errorMessage = ts('Related contact required fields are missing.');
-            array_unshift($values, $errorMessage);
-            return CRM_Import_Parser::NO_MATCH;
-          }
-
           //fixed for CRM-4148
           if (!empty($params[$key]['id'])) {
             $contact = [
@@ -1929,50 +1909,6 @@ public function processMessage(&$values, $statusFieldName, $returnCode) {
     return $returnCode;
   }
 
-  /**
-   * @param $relKey
-   * @param array $params
-   *
-   * @return bool
-   */
-  public function checkRelatedContactFields($relKey, $params) {
-    //avoid blank contact creation.
-    $allowToCreate = FALSE;
-
-    //build the mapper field array.
-    static $relatedContactFields = [];
-    if (!isset($relatedContactFields[$relKey])) {
-      foreach ($this->_mapperRelated as $key => $name) {
-        if (!$name) {
-          continue;
-        }
-
-        if (!empty($relatedContactFields[$name]) && !is_array($relatedContactFields[$name])) {
-          $relatedContactFields[$name] = [];
-        }
-        $fldName = $this->_mapperRelatedContactDetails[$key] ?? NULL;
-        if ($fldName == 'url') {
-          $fldName = 'website';
-        }
-        if ($fldName) {
-          $relatedContactFields[$name][] = $fldName;
-        }
-      }
-    }
-
-    //validate for passed data.
-    if (is_array($relatedContactFields[$relKey])) {
-      foreach ($relatedContactFields[$relKey] as $fld) {
-        if (!empty($params[$fld])) {
-          $allowToCreate = TRUE;
-          break;
-        }
-      }
-    }
-
-    return $allowToCreate;
-  }
-
   /**
    * get subtypes given the contact type
    *
@@ -3091,6 +3027,15 @@ public function getMappedRow(array $values): array {
   public function validateValues(array $values): void {
     $params = $this->getMappedRow($values);
     $this->validateRequiredContactFields($params['contact_type'], $params, $this->isUpdateExistingContacts());
+    foreach ($params as $key => $value) {
+      // If the key is a relationship key - eg. 5_a_b or 10_b_a
+      // then the value is an array that describes an existing contact.
+      // We need to check the fields are present to identify or create this
+      // contact.
+      if (preg_match('/^\d+_[a|b]_[a|b]$/', $key)) {
+        $this->validateRequiredContactFields($value['contact_type'], $value, TRUE, '(' . $this->getRelatedContactLabel(substr($key, 0, -4), substr($key, -3)) . ')');
+      }
+    }
 
     //check for duplicate external Identifier
     $externalID = $params['external_identifier'] ?? NULL;
@@ -3164,12 +3109,39 @@ protected function getRelatedContactType($relationshipTypeID, $relationshipDirec
     if (!$relationshipTypeID) {
       return NULL;
     }
-    $cacheKey = $relationshipTypeID . $relationshipDirection;
+    $relationshipField = 'contact_type_' . substr($relationshipDirection, -1);
+    return $this->getRelationshipType($relationshipTypeID, $relationshipDirection)[$relationshipField];
+  }
+
+  /**
+   * Get the related contact type.
+   *
+   * @param int|null $relationshipTypeID
+   * @param int|string $relationshipDirection
+   *
+   * @return null|string
+   *
+   * @throws \API_Exception
+   */
+  protected function getRelatedContactLabel($relationshipTypeID, $relationshipDirection): ?string {
+    $relationshipField = 'label_' . $relationshipDirection;
+    return $this->getRelationshipType($relationshipTypeID, $relationshipDirection)[$relationshipField];
+  }
+
+  /**
+   * Get the relationship type.
+   *
+   * @param int $relationshipTypeID
+   *
+   * @return string[]
+   * @throws \API_Exception
+   */
+  protected function getRelationshipType(int $relationshipTypeID): array {
+    $cacheKey = 'relationship_type' . $relationshipTypeID;
     if (!isset(Civi::$statics[__CLASS__][$cacheKey])) {
-      $relationshipField = 'contact_type_' . substr($relationshipDirection, -1);
       Civi::$statics[__CLASS__][$cacheKey] = RelationshipType::get(FALSE)
         ->addWhere('id', '=', $relationshipTypeID)
-        ->addSelect($relationshipField)->execute()->first()[$relationshipField];
+        ->addSelect('*')->execute()->first();
     }
     return Civi::$statics[__CLASS__][$cacheKey];
   }
diff --git a/CRM/Import/Parser.php b/CRM/Import/Parser.php
index 50109fe150b9..9e9465dfe1a9 100644
--- a/CRM/Import/Parser.php
+++ b/CRM/Import/Parser.php
@@ -512,11 +512,16 @@ public function setMaxLinesToProcess($max) {
    * @param string $contactType
    * @param array $params
    * @param bool $isPermitExistingMatchFields
+   *   True if the it is enough to have fields which will enable us to find
+   *   an existing contact (eg. external_identifier).
+   * @param string $prefixString
+   *   String to include in the exception (e.g '(Child of)' if we are validating
+   *   a related contact.
    *
    * @return void
    * @throws \CRM_Core_Exception
    */
-  protected function validateRequiredContactFields(string $contactType, array $params, bool $isPermitExistingMatchFields = TRUE): void {
+  protected function validateRequiredContactFields(string $contactType, array $params, bool $isPermitExistingMatchFields = TRUE, $prefixString = ''): void {
     if (!empty($params['id'])) {
       return;
     }
@@ -536,7 +541,7 @@ protected function validateRequiredContactFields(string $contactType, array $par
       // specified dedupe rule (or the default Unsupervised if not specified).
       $requiredFields['email'] = ts('Email Address');
     }
-    $this->validateRequiredFields($requiredFields, $params);
+    $this->validateRequiredFields($requiredFields, $params, $prefixString);
   }
 
   /**
@@ -1127,11 +1132,11 @@ protected function getIdsOfMatchingContacts(array $formatted):array {
    *     ['first_name' => ts('First Name'), 'last_name' => ts('Last Name')]
    *   ]
    *   Means 'email' OR 'first_name AND 'last_name'.
+   * @param string $prefixString
    *
-   * @throws \CRM_Core_Exception
-   *   Exception thrown if field requirements are not met.
+   * @throws \CRM_Core_Exception Exception thrown if field requirements are not met.
    */
-  protected function validateRequiredFields(array $requiredFields, array $params): void {
+  protected function validateRequiredFields(array $requiredFields, array $params, $prefixString): void {
     $missingFields = [];
     foreach ($requiredFields as $key => $required) {
       if (!is_array($required)) {
@@ -1163,7 +1168,7 @@ protected function validateRequiredFields(array $requiredFields, array $params):
         $missingFields[$key] = implode(' ' . ts('and') . ' ', $missing);
       }
     }
-    throw new CRM_Core_Exception(ts('Missing required fields:') . ' ' . implode(' ' . ts('OR') . ' ', $missingFields));
+    throw new CRM_Core_Exception(($prefixString ? ($prefixString . ' ') : '') . ts('Missing required fields:') . ' ' . implode(' ' . ts('OR') . ' ', $missingFields));
   }
 
 }
diff --git a/tests/phpunit/CRM/Contact/Import/Form/data/individual_invalid_with_related_phone.csv b/tests/phpunit/CRM/Contact/Import/Form/data/individual_invalid_with_related_phone.csv
new file mode 100644
index 000000000000..e1bb086ce329
--- /dev/null
+++ b/tests/phpunit/CRM/Contact/Import/Form/data/individual_invalid_with_related_phone.csv
@@ -0,0 +1,2 @@
+Player First Name,Player Last name,Mother – phone
+Susie,Jones,911
diff --git a/tests/phpunit/CRM/Contact/Import/Parser/ContactTest.php b/tests/phpunit/CRM/Contact/Import/Parser/ContactTest.php
index 899de1339c65..5df22b64a3d4 100644
--- a/tests/phpunit/CRM/Contact/Import/Parser/ContactTest.php
+++ b/tests/phpunit/CRM/Contact/Import/Parser/ContactTest.php
@@ -755,6 +755,16 @@ public function validateDataProvider(): array {
         'mapper' => [['last_name']],
         'expected_error' => 'Missing required fields: First Name OR Email Address',
       ],
+      'individual_related_required_met' => [
+        'csv' => 'individual_valid_with_related_email.csv',
+        'mapper' => [['first_name'], ['last_name'], ['1_a_b', 'email']],
+        'expected_error' => '',
+      ],
+      'individual_related_required_not_met' => [
+        'csv' => 'individual_invalid_with_related_phone.csv',
+        'mapper' => [['first_name'], ['last_name'], ['1_a_b', 'phone', 1, 2]],
+        'expected_error' => '(Child of) Missing required fields: First Name and Last Name OR Email Address OR External Identifier',
+      ],
       'individual_bad_email' => [
         'csv' => 'individual_invalid_email.csv',
         'mapper' => [['email', 1], ['first_name'], ['last_name']],