diff --git a/application/ADBWohneinheit/ADBWohneinheitModel.php b/application/ADBWohneinheit/ADBWohneinheitModel.php
index 49c3dc487..211ab60d2 100644
--- a/application/ADBWohneinheit/ADBWohneinheitModel.php
+++ b/application/ADBWohneinheit/ADBWohneinheitModel.php
@@ -54,6 +54,7 @@ class ADBWohneinheitModel {
             ORDER BY hausnummer_id,block,stiege,LENGTH(stock),stock,LENGTH(tuer),tuer,num
             LIMIT 1";
     
+    mfLoghandler::singleton()->debug($sql);
     $res = $db->query($sql);
     if($db->num_rows($res)) {
       $data = $db->fetch_object($res);
@@ -165,6 +166,15 @@ class ADBWohneinheitModel {
       }
     }
     
+    if(array_key_exists("oaid", $filter)) {
+      $oaid = FronkDB::singleton()->escape($filter['oaid']);
+      if(strlen($oaid)) {
+        $where .= " AND Wohneinheit.`oaid` = '$oaid'";
+      } else {
+        $where .= " AND (Wohneinheit.`oaid` IS NULL OR Wohneinheit.`oaid` = '')";
+      }
+    }
+    
     if(array_key_exists("num", $filter)) {
       $num = $filter['num'];
       if($num === false || $num === null) {
diff --git a/application/Api/v1/PreorderApicontroller.php b/application/Api/v1/PreorderApicontroller.php
index cb59c0c8e..1d0adf2a2 100644
--- a/application/Api/v1/PreorderApicontroller.php
+++ b/application/Api/v1/PreorderApicontroller.php
@@ -270,13 +270,13 @@ class PreorderApicontroller extends mfBaseApicontroller {
       $request_oaid = trim($this->post['address']->oaid);
       
       $m = [];
-      if($request_oaid && preg_match('/^([a-z]{2}-\d+-[0-9a-f]+)\.(\d+)/i', $request_oaid, $m)) {
+      if($request_oaid && preg_match('/^([a-z]{2}-\d+-[0-9a-f]+)(:?\.(\d+))?/i', $request_oaid, $m)) {
         if(array_key_exists(1, $m)) {
           $request_oaid_hausnummer = $m[1];
         }
         
         if(array_key_exists(2, $m)) {
-          $request_oaid_unit = "$request_oaid_hausnummer.".$m[2];
+          $request_oaid_unit = "$request_oaid_hausnummer".$m[2];
         }
       }
     }
@@ -290,7 +290,7 @@ class PreorderApicontroller extends mfBaseApicontroller {
      * check address
      */
     //var_dump($request_oaid_unit);exit;
-    if(!$request_oaid_unit) {
+    if(!$request_oaid_hausnummer) {
       if(!property_exists($this->post['address'],"street") || !$this->post['address']->street ||
          !property_exists($this->post['address'],"housenumber") || !$this->post['address']->housenumber ||
          !property_exists($this->post['address'],"zip") || !$this->post['address']->zip ||
@@ -367,9 +367,16 @@ class PreorderApicontroller extends mfBaseApicontroller {
      * search address in AddressDB
      */
     if($request_oaid_hausnummer) {
-      $res = $this->db()->select("view_hausnummer", "*", "oaid='$request_oaid_hausnummer'");
+      
+      $where = "oaid='$request_oaid_hausnummer'";
+      
+      if(count($this->filter_salescluster_ids)) {
+        $where .= " AND netzgebiet_id IN (".implode(',', $this->filter_salescluster_ids).")";
+      }
+      
+      $res = $this->db()->select("view_hausnummer", "*", $where);
       if(!$this->db()->num_rows($res)) {
-        return mfResponse::NotFound(["message" => "OAID nicht gefunden"]);
+        return mfResponse::NotFound(["message" => "OAID not found"]);
       }
       $address = $this->db()->fetch_object($res);
     } else {
@@ -431,13 +438,29 @@ class PreorderApicontroller extends mfBaseApicontroller {
     $where = "1=1 ";
     $unit = false;
     
+    $unit_search_count_without_stock = count($unit_search);
+    if(array_key_exists("stock", $unit_search) && $unit_search['stock']) {
+      $unit_search_count_without_stock--;
+    }
+    
     if($request_oaid_unit) {
-      $unit = ADBWohneinheitModel::getFirst(["oaid" => $request_oaid_unit]);
+      $where = "wohneinheit_oaid='$request_oaid_unit'";
+      if(count($this->filter_salescluster_ids)) {
+        $where .= " AND netzgebiet_id IN (".implode(',', $this->filter_salescluster_ids).")";
+      }
+      //$unit = ADBWohneinheitModel::getFirst(["oaid" => $request_oaid_unit]);
+      $res = $this->db()->select("view_wohneinheit", "*", $where);
+      if($this->db()->num_rows($res)) {
+        $unit = $this->db()->fetch_object($res);
+      }
       if(!$unit) {
         return mfResponse::NotFound(["message" => "Wohneinheit nicht gefunden"]);
       }
+      if(count($unit_search)) {
+        $update_unit = true;
+      }
       
-    } elseif(count($unit_search)) {
+    } elseif($unit_search_count_without_stock > 0) {
       //var_dump($unit_search);exit;
       if(array_key_exists("unit_string", $unit_search)) {
         $where .= " AND bezeichner LIKE '".$unit_search['unit_string']."'";
@@ -480,7 +503,7 @@ class PreorderApicontroller extends mfBaseApicontroller {
       if($this->db()->num_rows($res)) {
         $unit = $this->db()->fetch_object($res);
       } else {
-        // XXX
+        // XXX - If there are no units without unit data maybe try finding a fitting unit without an order
         //$assign_unit = true;
       }
     }
@@ -662,38 +685,51 @@ class PreorderApicontroller extends mfBaseApicontroller {
       //var_dump($unit);
       //exit;
       
-      // get available units
-      $exclude_wohneinheit_ids = [];
-      $preorders_in_hausnummer = PreorderModel::search(['adb_hausnummer_id' => $address->hausnummer_id]);
-      if(count($preorders_in_hausnummer)) {
-        
-        foreach($preorders_in_hausnummer as $pih) {
-          if($pih->adb_wohneinheit_id) {
-            $exclude_wohneinheit_ids[] = $pih->adb_wohneinheit_id;
+      if($request_oaid_unit) {
+        // if unit oaid is set, we know our unit already
+        $unit = new ADBWohneinheit($unit->wohneinheit_id);
+        if($unit->block || $unit->stiege || $unit->stock || $unit->tuer) {
+          foreach(["block", "stiege", "stock", "tuer"] as $type) {
+            if($unit->$type && $unit->$type != $unit_search[$type]) {
+              return mfResponse::Forbidden(['message' => "Überschreiben von Wohneinheitsdaten nicht erlaubt"]);
+            }
           }
         }
+      } else {
+        // else get available units with no unit data, so we can update it
+        $exclude_wohneinheit_ids = [];
+        $preorders_in_hausnummer = PreorderModel::search(['adb_hausnummer_id' => $address->hausnummer_id]);
+        if(count($preorders_in_hausnummer)) {
+
+          foreach($preorders_in_hausnummer as $pih) {
+            if($pih->adb_wohneinheit_id) {
+              $exclude_wohneinheit_ids[] = $pih->adb_wohneinheit_id;
+            }
+          }
+        }
+
+        // get units excluding unavailable units
+        $where = "hausnummer_id=".$address->hausnummer_id;
+        $where .= " AND ( block = '' OR block IS NULL)";
+        $where .= " AND ( stiege = '' OR stiege IS NULL)";
+        $where .= " AND ( stock = '' OR stock IS NULL)";
+        $where .= " AND ( tuer = '' OR tuer IS NULL)";
+        $where .= " AND ( bezeichner = '' OR bezeichner IS NULL)";
+
+        if(count($exclude_wohneinheit_ids)) {
+          $where .= " AND wohneinheit_id NOT IN (". implode(",",$exclude_wohneinheit_ids).")";
+        }
+        $sql = "SELECT * FROM view_wohneinheit WHERE $where";
+        $this->log->debug($sql);
+        $res = $this->db()->query($sql);
+        if(!$this->db()->num_rows($res)) {
+          return mfResponse::Forbidden(['message' => "Keine Wohneinheiten verfügbar"]);
+        }
+
+        $unit_row = $this->db()->fetch_object($res);
+        $unit = new ADBWohneinheit($unit_row->wohneinheit_id);
       }
       
-      // get units excluding unavailable units
-      $where = "hausnummer_id=".$address->hausnummer_id;
-      $where .= " AND ( block = '' OR block IS NULL)";
-      $where .= " AND ( stiege = '' OR stiege IS NULL)";
-      $where .= " AND ( stock = '' OR stock IS NULL)";
-      $where .= " AND ( tuer = '' OR tuer IS NULL)";
-      $where .= " AND ( bezeichner = '' OR bezeichner IS NULL)";
-      
-      if(count($exclude_wohneinheit_ids)) {
-        $where .= " AND wohneinheit_id NOT IN (". implode(",",$exclude_wohneinheit_ids).")";
-      }
-      $sql = "SELECT * FROM view_wohneinheit WHERE $where";
-      $this->log->debug($sql);
-      $res = $this->db()->query($sql);
-      if(!$this->db()->num_rows($res)) {
-        return mfResponse::Forbidden(['message' => "Keine Wohneinheiten verfügbar"]);
-      }
-      
-      $unit_row = $this->db()->fetch_object($res);
-      $unit = new ADBWohneinheit($unit_row->wohneinheit_id);
       if(!$unit->id) {
         return mfResponse::InternalServerError(['message' => "unit not found"]);
       }
@@ -701,7 +737,7 @@ class PreorderApicontroller extends mfBaseApicontroller {
       
       $change_note_data = [];
       foreach(['block','stiege','stock','tuer','bezeichner'] as $unit_address_part) {
-        if($unit_search[$unit_address_part]) {
+        if($unit_search[$unit_address_part] && $unit_search[$unit_address_part] != $unit->$unit_address_part) {
           $unit->$unit_address_part = $unit_search[$unit_address_part];
           $unit_changed = true;
           $change_note_data[] = [