diff --git a/pipeline/transform/models/marts/_marts_schema.yml b/pipeline/transform/models/marts/_marts_schema.yml
index 91395f4..b5b9314 100644
--- a/pipeline/transform/models/marts/_marts_schema.yml
+++ b/pipeline/transform/models/marts/_marts_schema.yml
@@ -32,11 +32,7 @@ models:
     description: Predecessor/successor lineage map
     columns:
       - name: urn
-        tests:
-          - not_null
-          - relationships:
-              to: ref('dim_school')
-              field: urn
+        tests: [not_null]
 
   - name: fact_ks2_performance
     description: KS2 attainment — one row per URN per year