diff --git a/validation/chpa/01_dwd/validate_hierarchy_refactor.sql b/validation/chpa/01_dwd/validate_hierarchy_refactor.sql
index 6983f97..23152c0 100644
--- a/validation/chpa/01_dwd/validate_hierarchy_refactor.sql
+++ b/validation/chpa/01_dwd/validate_hierarchy_refactor.sql
@@ -134,6 +134,7 @@ LEFT JOIN nfc_level_3
 -- COMMAND ----------
 
 -- Every check must return passed = true before replacing the scheduled jobs.
+CREATE OR REPLACE TEMP VIEW validation_hierarchy_compatibility_checks AS
 WITH compatibility_checks AS (
     SELECT
         'atc_row_count' AS check_name,
@@ -145,9 +146,35 @@ WITH compatibility_checks AS (
         (
             SELECT COUNT(*)
             FROM (
-                SELECT * FROM dwd.dwd_ims_atc_hierarchy
+                SELECT
+                    ATC1_ID,
+                    ATC1_CODE,
+                    ATC1_DES,
+                    ATC2_ID,
+                    ATC2_CODE,
+                    ATC2_DES,
+                    ATC3_ID,
+                    ATC3_CODE,
+                    ATC3_DES,
+                    ATC4_ID,
+                    ATC4_CODE,
+                    ATC4_DES
+                FROM dwd.dwd_ims_atc_hierarchy
                 EXCEPT ALL
-                SELECT * FROM validation_atc_hierarchy_candidate
+                SELECT
+                    ATC1_ID,
+                    ATC1_CODE,
+                    ATC1_DES,
+                    ATC2_ID,
+                    ATC2_CODE,
+                    ATC2_DES,
+                    ATC3_ID,
+                    ATC3_CODE,
+                    ATC3_DES,
+                    ATC4_ID,
+                    ATC4_CODE,
+                    ATC4_DES
+                FROM validation_atc_hierarchy_candidate
             ) AS differences
         ) AS actual_value,
         0 AS expected_value
@@ -157,9 +184,35 @@ WITH compatibility_checks AS (
         (
             SELECT COUNT(*)
             FROM (
-                SELECT * FROM validation_atc_hierarchy_candidate
+                SELECT
+                    ATC1_ID,
+                    ATC1_CODE,
+                    ATC1_DES,
+                    ATC2_ID,
+                    ATC2_CODE,
+                    ATC2_DES,
+                    ATC3_ID,
+                    ATC3_CODE,
+                    ATC3_DES,
+                    ATC4_ID,
+                    ATC4_CODE,
+                    ATC4_DES
+                FROM validation_atc_hierarchy_candidate
                 EXCEPT ALL
-                SELECT * FROM dwd.dwd_ims_atc_hierarchy
+                SELECT
+                    ATC1_ID,
+                    ATC1_CODE,
+                    ATC1_DES,
+                    ATC2_ID,
+                    ATC2_CODE,
+                    ATC2_DES,
+                    ATC3_ID,
+                    ATC3_CODE,
+                    ATC3_DES,
+                    ATC4_ID,
+                    ATC4_CODE,
+                    ATC4_DES
+                FROM dwd.dwd_ims_atc_hierarchy
             ) AS differences
         ) AS actual_value,
         0 AS expected_value
@@ -174,9 +227,29 @@ WITH compatibility_checks AS (
         (
             SELECT COUNT(*)
             FROM (
-                SELECT * FROM dwd.dwd_ims_nfc_hierarchy
+                SELECT
+                    NFC1_ID,
+                    NFC1_CODE,
+                    NFC1_DES,
+                    NFC2_ID,
+                    NFC2_CODE,
+                    NFC2_DES,
+                    NFC3_ID,
+                    NFC3_CODE,
+                    NFC3_DES
+                FROM dwd.dwd_ims_nfc_hierarchy
                 EXCEPT ALL
-                SELECT * FROM validation_nfc_hierarchy_candidate
+                SELECT
+                    NFC1_ID,
+                    NFC1_CODE,
+                    NFC1_DES,
+                    NFC2_ID,
+                    NFC2_CODE,
+                    NFC2_DES,
+                    NFC3_ID,
+                    NFC3_CODE,
+                    NFC3_DES
+                FROM validation_nfc_hierarchy_candidate
             ) AS differences
         ) AS actual_value,
         0 AS expected_value
@@ -186,9 +259,41 @@ WITH compatibility_checks AS (
         (
             SELECT COUNT(*)
             FROM (
-                SELECT * FROM validation_nfc_hierarchy_candidate
+                SELECT
+                    NFC1_ID,
+                    NFC1_CODE,
+                    NFC1_DES,
+                    NFC2_ID,
+                    NFC2_CODE,
+                    NFC2_DES,
+                    NFC3_ID,
+                    NFC3_CODE,
+                    NFC3_DES
+                FROM validation_nfc_hierarchy_candidate
                 EXCEPT ALL
-                SELECT * FROM dwd.dwd_ims_nfc_hierarchy
+                SELECT
+                    NFC1_ID,
+                    NFC1_CODE,
+                    NFC1_DES,
+                    NFC2_ID,
+                    NFC2_CODE,
+                    NFC2_DES,
+                    NFC3_ID,
+                    NFC3_CODE,
+                    NFC3_DES
+                FROM dwd.dwd_ims_nfc_hierarchy
+            ) AS differences
+        ) AS actual_value,
+        0 AS expected_value
+    UNION ALL
+    SELECT
+        'except_all_null_semantics' AS check_name,
+        (
+            SELECT COUNT(*)
+            FROM (
+                SELECT CAST(NULL AS STRING) AS nullable_value
+                EXCEPT ALL
+                SELECT CAST(NULL AS STRING) AS nullable_value
             ) AS differences
         ) AS actual_value,
         0 AS expected_value
@@ -199,6 +304,16 @@ SELECT
     expected_value,
     actual_value = expected_value AS passed
 FROM compatibility_checks
+;
+
+-- COMMAND ----------
+
+SELECT
+    check_name,
+    actual_value,
+    expected_value,
+    passed
+FROM validation_hierarchy_compatibility_checks
 ORDER BY check_name;
 
 -- COMMAND ----------
@@ -222,9 +337,10 @@ SELECT
 FROM atc_duplicate_paths
 UNION ALL
 SELECT
-    'atc_null_root_code' AS metric_name,
-    COUNT_IF(ATC1_CODE IS NULL) AS metric_value
-FROM validation_atc_hierarchy_candidate
+    'atc_source_level_1_required_key_null' AS metric_name,
+    COUNT_IF(therapeutic_id IS NULL OR therapeutic_code IS NULL) AS metric_value
+FROM dwd.dwd_ims_td_therapeutic_class
+WHERE therapeutic_level = '1'
 UNION ALL
 SELECT
     'atc_unmatched_level_2' AS metric_name,
@@ -247,9 +363,10 @@ SELECT
 FROM nfc_duplicate_paths
 UNION ALL
 SELECT
-    'nfc_null_root_code' AS metric_name,
-    COUNT_IF(NFC1_CODE IS NULL) AS metric_value
-FROM validation_nfc_hierarchy_candidate
+    'nfc_source_level_1_required_key_null' AS metric_name,
+    COUNT_IF(newformclass_id IS NULL OR newformclass_code IS NULL) AS metric_value
+FROM dwd.dwd_ims_td_new_form_class
+WHERE newformclass_level = '1'
 UNION ALL
 SELECT
     'nfc_unmatched_level_2' AS metric_name,
@@ -261,3 +378,19 @@ SELECT
     COUNT_IF(NFC3_CODE IS NULL) AS metric_value
 FROM validation_nfc_hierarchy_candidate
 ORDER BY metric_name;
+
+-- COMMAND ----------
+
+-- Abort the notebook when any compatibility check fails.
+SELECT IF(
+    COUNT_IF(NOT passed) = 0,
+    'All hierarchy compatibility checks passed.',
+    raise_error(
+        CONCAT(
+            'Hierarchy compatibility validation failed: ',
+            CAST(COUNT_IF(NOT passed) AS STRING),
+            ' check(s) did not pass.'
+        )
+    )
+) AS validation_result
+FROM validation_hierarchy_compatibility_checks;