diff --git a/app/Classes/Modules/Segments/ControllersLogic/UpdateConstantPostcodeLogic.php b/app/Classes/Modules/Segments/ControllersLogic/UpdateConstantPostcodeLogic.php
index 82edc1a2..f39fdb29 100644
--- a/app/Classes/Modules/Segments/ControllersLogic/UpdateConstantPostcodeLogic.php
+++ b/app/Classes/Modules/Segments/ControllersLogic/UpdateConstantPostcodeLogic.php
@@ -14,6 +14,8 @@ use App\Classes\Modules\Segments\Standards\Rules\CanUpdateConstant;
 use App\Classes\Modules\Segments\DataTransferObjects\ConstantObject;
 use App\Classes\Modules\Segments\Services\AddItemToConstantValueArray;
 use App\Classes\Modules\Segments\Services\RemoveItemFromConstantValueArray;
+use App\Classes\Exceptions\ResourceNotFoundException;
+use App\Classes\Modules\Segments\Services\CreatesConstant;
 
 class UpdateConstantPostcodeLogic  extends AbstractControllerLogic
 {
@@ -46,6 +48,8 @@ class UpdateConstantPostcodeLogic  extends AbstractControllerLogic
     /** @var RemoveItemFromConstantValueArray */
     private $removeItemFromConstantValueArray;
 
+    /** @var CreatesConstant */
+    private $createsConstant;
 
     /**
      * UpdateConstantLogic constructor.
@@ -54,9 +58,18 @@ class UpdateConstantPostcodeLogic  extends AbstractControllerLogic
      * @param FetchesSegment $fetchesSegment
      * @param FetchesConstant $fetchesConstant
      * @param AddItemToConstantValueArray $addItemToConstantValueArray
+     * @param CreatesConstant $createsConstant
      * @param RemoveItemFromConstantValueArray $removeItemFromConstantValueArray
      */
-    public function __construct(CanUpdateConstant $canUpdateConstant, UpdatesConstant $updatesConstant, FetchesSegment $fetchesSegment, FetchesConstant $fetchesConstant,AddItemToConstantValueArray $addItemToConstantValueArray, RemoveItemFromConstantValueArray $removeItemFromConstantValueArray)
+    public function __construct(
+        CanUpdateConstant $canUpdateConstant, 
+        UpdatesConstant $updatesConstant, 
+        FetchesSegment $fetchesSegment, 
+        FetchesConstant $fetchesConstant,
+        AddItemToConstantValueArray $addItemToConstantValueArray, 
+        RemoveItemFromConstantValueArray $removeItemFromConstantValueArray,
+        CreatesConstant $createsConstant
+    )
     {
         $this->canUpdateConstant = $canUpdateConstant;
         $this->updatesConstant = $updatesConstant;
@@ -64,6 +77,7 @@ class UpdateConstantPostcodeLogic  extends AbstractControllerLogic
         $this->fetchesConstant = $fetchesConstant;
         $this->addItemToConstantValueArray = $addItemToConstantValueArray;
         $this->removeItemFromConstantValueArray = $removeItemFromConstantValueArray;
+        $this->createsConstant = $createsConstant;
     }
     /**
      * @param Request $request
@@ -76,24 +90,42 @@ class UpdateConstantPostcodeLogic  extends AbstractControllerLogic
     {
         $segment = $this->fetchesSegment->execute(['id' => $request->route('id')]);
 
-        $constant = $this->fetchesConstant->execute(['segment_id' => $segment->id, 'reference' => $request->input('reference')]);
+        try {
+            $constant = $this->fetchesConstant->execute(['segment_id' => $segment->id, 'reference' => $request->input('reference')]);
 
-        $object = new ConstantObject($constant->reference, $this->addItemToConstantValueArray->execute($constant->value, $request->input('postcode')));
-        $this->canUpdateConstant->passes($object);
+            $constantValue = $this->addItemToConstantValueArray->execute($constant->value, $request->input('postcode'));
+
+            $object = new ConstantObject($request->input('reference'), $constantValue);
+
+        } catch (ResourceNotFoundException $exception){
+
+            $constantObject = [$request->input('postcode')];
+
+            $object = new ConstantObject(
+                $request->input('reference'),
+                $constantObject
+            );
+
+            $constant = $this->createsConstant->execute($segment, $object);
+        }
+
+        try {
+            // check if postcode exist in the opposite constant, and delete it
+            $oppositeConstant = $this->fetchesConstant->execute(['segment_id' => $segment->id, 'reference' => $request->input('reference') == SegmentConstants::CENTER_POSTCODE ? SegmentConstants::OUTSTATION_POSTCODE : SegmentConstants::CENTER_POSTCODE]);
+
+            $oppositeConstantValue = $this->removeItemFromConstantValueArray->execute($oppositeConstant->value, $request->input('postcode'));
+
+            $oppositeObject = new ConstantObject($request->input('reference') == SegmentConstants::CENTER_POSTCODE ? SegmentConstants::OUTSTATION_POSTCODE : SegmentConstants::CENTER_POSTCODE, $oppositeConstantValue);
+
+            $this->updatesConstant->execute($oppositeConstant, $oppositeObject);
+
+        } catch (ResourceNotFoundException $exception){
+            // if opposite constant does not exist, do nothing
+        }
 
         $constant = $this->updatesConstant->execute($constant, $object);
 
-        $oppositeConstant = $this->fetchesConstant->execute(['segment_id' => $segment->id, 'reference' => $request->input('reference') == SegmentConstants::CENTER_POSTCODE ? SegmentConstants::OUTSTATION_POSTCODE : SegmentConstants::CENTER_POSTCODE]);
-
-        $oppositeObject = new ConstantObject($request->input('reference') == SegmentConstants::CENTER_POSTCODE ? SegmentConstants::OUTSTATION_POSTCODE : SegmentConstants::CENTER_POSTCODE, $this->removeItemFromConstantValueArray->execute($oppositeConstant->value, $request->input('postcode')));
-
-        $oppositeConstant = $this->updatesConstant->execute($oppositeConstant, $oppositeObject);
-
-
-        return $this->response([
-            'CENTER_POSTCODE' => $constant->reference == SegmentConstants::CENTER_POSTCODE ? new ConstantResource($constant) : New ConstantResource($oppositeConstant),
-            'OUTSTATION_POSTCODE' => $constant->reference == SegmentConstants::OUTSTATION_POSTCODE ? new ConstantResource($constant) : New ConstantResource($oppositeConstant),
-        ]);
+        return $this->resourceResponse(new ConstantResource($constant));
     }
 
 }
\ No newline at end of file