diff --git a/applications/modelling_e2e/handler.py b/applications/modelling_e2e/handler.py
index b580a37d4..55a646676 100644
--- a/applications/modelling_e2e/handler.py
+++ b/applications/modelling_e2e/handler.py
@@ -205,13 +205,21 @@ def _flush_writes(engine: Engine, writes: list[_PropertyWrite]) -> None:
             uow.epc.save_batch(lodged_requests)
         if predicted_requests:
             uow.epc.save_batch(predicted_requests)
+        # First plan wins: a property with no default Plan yet gets this Plan
+        # as its default whatever the Scenario's flag says (the legacy
+        # p.is_new rule — readers select one default Plan per property, so a
+        # first run under a non-default Scenario must still produce one).
+        # Also heals properties left default-less by runs before this rule.
+        have_default: set[int] = uow.plan.property_ids_with_default_plans(
+            [w.property_id for w in writes]
+        )
         plan_requests = [
             PlanSaveRequest(
                 w.plan,
                 property_id=w.property_id,
                 scenario_id=w.scenario_id,
                 portfolio_id=w.portfolio_id,
-                is_default=w.is_default,
+                is_default=w.is_default or w.property_id not in have_default,
             )
             for w in writes
         ]