diff --git a/template/types/methods/constructors/default.php b/template/types/methods/constructors/default.php
index 11a00cf3..394d4c5f 100644
--- a/template/types/methods/constructors/default.php
+++ b/template/types/methods/constructors/default.php
@@ -56,7 +56,11 @@ public function __construct(null|array<?php if ($type->isValueContainer()) : ?>|
             }
         }<?php endif; ?>
 
-<?php foreach($properties as $property) :
+        $_parsed = [];
+        foreach($data as $field => $value) {
+<?php
+$propertyIndex = 0;
+foreach($properties as $property) :
     if ($property->isOverloaded()) {
         continue;
     }
@@ -66,6 +70,7 @@ public function __construct(null|array<?php if ($type->isValueContainer()) : ?>|
                 [
                     'config' => $config,
                     'type' => $type,
+                    'propertyIndex' => $propertyIndex,
                     'property' => $property,
                 ]
         );
@@ -75,10 +80,14 @@ public function __construct(null|array<?php if ($type->isValueContainer()) : ?>|
                 [
                     'config' => $config,
                     'type' => $type,
+                    'propertyIndex' => $propertyIndex,
                     'property' => $property
                 ]
         );
     endif;
+    $propertyIndex++;
 endforeach; ?>
+
+        }
     }
 <?php return ob_get_clean();
\ No newline at end of file
diff --git a/template/types/methods/constructors/default_property_setter_call.php b/template/types/methods/constructors/default_property_setter_call.php
index 54d56fa9..8d6e804f 100644
--- a/template/types/methods/constructors/default_property_setter_call.php
+++ b/template/types/methods/constructors/default_property_setter_call.php
@@ -21,12 +21,14 @@
 /** @var \DCarbone\PHPFHIR\Config\VersionConfig $config */
 /** @var \DCarbone\PHPFHIR\Definition\Type $type */
 /** @var \DCarbone\PHPFHIR\Definition\Property $property */
+/** @var int $propertyIndex */
 
 $propertyType = $property->getValueFHIRType();
 $fieldConstantName = $property->getFieldConstantName();
 
 $requireArgs = [
     'config' => $config,
+    'propertyIndex' => $propertyIndex,
     'property' => $property
 ];
 
diff --git a/template/types/methods/constructors/primitive_container.php b/template/types/methods/constructors/primitive_container.php
index 44988235..91b981e8 100644
--- a/template/types/methods/constructors/primitive_container.php
+++ b/template/types/methods/constructors/primitive_container.php
@@ -59,7 +59,9 @@ public function __construct(<?php echo TypeHintUtils::propertySetterTypeHint($co
                 $this->_addFHIRComment($data[PHPFHIRConstants::JSON_FIELD_FHIR_COMMENTS]);
             }
         }<?php endif; ?>
-<?php foreach ($properties as $property) :
+<?php
+$propertyIndex = 0;
+foreach ($properties as $property) :
     if ($property->isOverloaded()) :
         continue;
     endif;
@@ -68,9 +70,12 @@ public function __construct(<?php echo TypeHintUtils::propertySetterTypeHint($co
             [
                 'config' => $config,
                 'type' => $type,
+                'propertyIndex' => $propertyIndex,
                 'property' => $property,
             ]
     );
+    $propertyIndex++;
 endforeach; ?>
+
     }
 <?php return ob_get_clean();
diff --git a/template/types/methods/constructors/property_setter_default.php b/template/types/methods/constructors/property_setter_default.php
index 05ecf69b..bbcb4408 100644
--- a/template/types/methods/constructors/property_setter_default.php
+++ b/template/types/methods/constructors/property_setter_default.php
@@ -16,36 +16,38 @@
  * limitations under the License.
  */
 
+/** @var \DCarbone\PHPFHIR\Config $config */
 /** @var \DCarbone\PHPFHIR\Definition\Property $property */
+/** @var int $propertyIndex */
 
 $propertyTypeClassName = $property->getValueFHIRType()->getClassName();
 $propertyFieldConst = $property->getFieldConstantName();
 $propertyFieldConstExt = $property->getFieldConstantExtensionName();
 $setter = $property->getSetterName();
 
-ob_start(); ?>
-        if (array_key_exists(self::<?php echo $propertyFieldConst; ?>, $data)) {
+ob_start();
+if (0 === $propertyIndex) : ?>
+            if <?php else : ?> else if <?php endif; ?>(self::<?php echo $propertyFieldConst; ?> === $field) {
 <?php if ($property->isCollection()) : ?>
-            if (is_array($data[self::<?php echo $propertyFieldConst; ?>])) {
-                foreach($data[self::<?php echo $propertyFieldConst; ?>] as $v) {
-                    if ($v instanceof <?php echo $propertyTypeClassName; ?>) {
-                        $this-><?php echo $setter; ?>($v);
-                    } else {
-                        $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($v));
+                if (is_array($value)) {
+                    foreach($value as $v) {
+                        if ($v instanceof <?php echo $propertyTypeClassName; ?>) {
+                            $this-><?php echo $setter; ?>($v);
+                        } else {
+                            $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($v));
+                        }
                     }
+                } elseif ($value instanceof <?php echo $propertyTypeClassName; ?>) {
+                    $this-><?php echo $setter; ?>($value);
+                } else {
+                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($value));
                 }
-            } elseif ($data[self::<?php echo $propertyFieldConst; ?>] instanceof <?php echo $propertyTypeClassName; ?>) {
-                $this-><?php echo $setter; ?>($data[self::<?php echo $propertyFieldConst; ?>]);
-            } else {
-                $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($data[self::<?php echo $propertyFieldConst; ?>]));
-            }
 <?php else : ?>
-            if ($data[self::<?php echo $propertyFieldConst; ?>] instanceof <?php echo $propertyTypeClassName; ?>) {
-                $this-><?php echo $setter; ?>($data[self::<?php echo $propertyFieldConst; ?>]);
-            } else {
-                $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($data[self::<?php echo $propertyFieldConst; ?>]));
-            }
+                if ($value instanceof <?php echo $propertyTypeClassName; ?>) {
+                    $this-><?php echo $setter; ?>($value);
+                } else {
+                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($value));
+                }
 <?php endif; ?>
-        }
-<?php
+            }<?php
 return ob_get_clean(); ?>
diff --git a/template/types/methods/constructors/property_setter_primitive.php b/template/types/methods/constructors/property_setter_primitive.php
index af9b9700..62d2061f 100644
--- a/template/types/methods/constructors/property_setter_primitive.php
+++ b/template/types/methods/constructors/property_setter_primitive.php
@@ -16,33 +16,35 @@
  * limitations under the License.
  */
 
+/** @var \DCarbone\PHPFHIR\Config $config */
 /** @var \DCarbone\PHPFHIR\Definition\Property $property */
+/** @var int $propertyIndex */
 
 $propertyFieldConst = $property->getFieldConstantName();
 $setter = $property->getSetterName();
 
-ob_start(); ?>
-        if (array_key_exists(self::<?php echo $propertyFieldConst; ?>, $data)) {
+ob_start();
+if (0 === $propertyIndex) : ?>
+            if <?php else : ?> else if <?php endif; ?>(self::<?php echo $propertyFieldConst; ?> === $field) {
 <?php if ($property->isCollection()) : ?>
-            if (is_array($data[self::<?php echo $propertyFieldConst; ?>])) {
-                foreach($data[self::<?php echo $propertyFieldConst; ?>] as $v) {
-                    if (!($v instanceof <?php echo $property->getValueFHIRType()->getClassName(); ?>)) {
-                        $v = new <?php echo $property->getValueFHIRType()->getClassName(); ?>($v);
+                if (is_array($value)) {
+                    foreach($value as $v) {
+                        if (!($v instanceof <?php echo $property->getValueFHIRType()->getClassName(); ?>)) {
+                            $v = new <?php echo $property->getValueFHIRType()->getClassName(); ?>($v);
+                        }
+                        $this-><?php echo $setter; ?>($v);
                     }
-                    $this-><?php echo $setter; ?>($v);
+                } else if ($value instanceof <?php echo $property->getValueFHIRType()->getClassName(); ?>) {
+                    $this-><?php echo $setter; ?>($data[self::<?php echo $propertyFieldConst; ?>]);
+                } else {
+                    $this-><?php echo $setter; ?>(new <?php echo $property->getValueFHIRType()->getClassName(); ?>($value));
                 }
-            } else if ($data[self::<?php echo $propertyFieldConst; ?>] instanceof <?php echo $property->getValueFHIRType()->getClassName(); ?>) {
-                $this-><?php echo $setter; ?>($data[self::<?php echo $propertyFieldConst; ?>]);
-            } else {
-                $this-><?php echo $setter; ?>(new <?php echo $property->getValueFHIRType()->getClassName(); ?>($data[self::<?php echo $propertyFieldConst; ?>]));
-            }
 <?php else : ?>
-            if ($data[self::<?php echo $propertyFieldConst; ?>] instanceof <?php echo $property->getvalueFHIRType()->getClassName(); ?>) {
-                $this-><?php echo $setter; ?>($data[self::<?php echo $propertyFieldConst; ?>]);
-            } else {
-                $this-><?php echo $setter; ?>(new <?php echo $property->getValueFHIRType()->getClassName(); ?>($data[self::<?php echo $propertyFieldConst; ?>]));
-            }
+                if ($value instanceof <?php echo $property->getvalueFHIRType()->getClassName(); ?>) {
+                    $this-><?php echo $setter; ?>($value);
+                } else {
+                    $this-><?php echo $setter; ?>(new <?php echo $property->getValueFHIRType()->getClassName(); ?>($value));
+                }
 <?php endif; ?>
-        }
-<?php
+            }<?php
 return ob_get_clean();
diff --git a/template/types/methods/constructors/property_setter_primitive_container.php b/template/types/methods/constructors/property_setter_primitive_container.php
index b1afb79f..c19d4f4e 100644
--- a/template/types/methods/constructors/property_setter_primitive_container.php
+++ b/template/types/methods/constructors/property_setter_primitive_container.php
@@ -16,8 +16,9 @@
  * limitations under the License.
  */
 
-/** @var \DCarbone\PHPFHIR\Config\VersionConfig $configf */
+/** @var \DCarbone\PHPFHIR\Config\VersionConfig $config */
 /** @var \DCarbone\PHPFHIR\Definition\Property $property */
+/** @var int $propertyIndex */
 
 $propertyTypeClassName = $property->getValueFHIRType()->getClassName();
 $propertyFieldConst = $property->getFieldConstantName();
@@ -26,42 +27,43 @@
 
 // these types are a pain in the ass
 
-ob_start(); ?>
-        if (array_key_exists(self::<?php echo $propertyFieldConst; ?>, $data) || array_key_exists(self::<?php echo $propertyFieldConstExt; ?>, $data)) {
-            $value = $data[self::<?php echo $propertyFieldConst; ?>] ?? null;
-            $ext = (isset($data[self::<?php echo $propertyFieldConstExt; ?>]) && is_array($data[self::<?php echo $propertyFieldConstExt; ?>])) ? $data[self::<?php echo $propertyFieldConstExt; ?>] : [];
-            if (null !== $value) {
-                if ($value instanceof <?php echo $propertyTypeClassName; ?>) {
-                    $this-><?php echo $setter; ?>($value);
-                } else <?php if ($property->isCollection()) : ?>if (is_array($value)) {
-                    foreach($value as $i => $v) {
-                        if ($v instanceof <?php echo $propertyTypeClassName; ?>) {
-                            $this-><?php echo $setter; ?>($v);
-                        } else {
-                            $iext = (isset($ext[$i]) && is_array($ext[$i])) ? $ext[$i] : [];
-                            if (is_array($v)) {
-                                $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>(array_merge($v, $iext)));
+ob_start();
+if (0 === $propertyIndex) : ?>
+            if <?php else : ?> else if <?php endif; ?>((self::<?php echo $propertyFieldConst; ?> === $field || self::<?php echo $propertyFieldConstExt; ?> === $field) && !isset($_parsed[self::<?php echo $propertyFieldConst; ?>])) {
+                $value = $data[self::<?php echo $propertyFieldConst; ?>] ?? null;
+                $ext = (isset($data[self::<?php echo $propertyFieldConstExt; ?>]) && is_array($data[self::<?php echo $propertyFieldConstExt; ?>])) ? $data[self::<?php echo $propertyFieldConstExt; ?>] : [];
+                if (null !== $value) {
+                    if ($value instanceof <?php echo $propertyTypeClassName; ?>) {
+                        $this-><?php echo $setter; ?>($value);
+                    } else <?php if ($property->isCollection()) : ?>if (is_array($value)) {
+                        foreach($value as $i => $v) {
+                            if ($v instanceof <?php echo $propertyTypeClassName; ?>) {
+                                $this-><?php echo $setter; ?>($v);
                             } else {
-                                $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>([<?php echo $propertyTypeClassName; ?>::FIELD_VALUE => $v] + $iext));
+                                $iext = (isset($ext[$i]) && is_array($ext[$i])) ? $ext[$i] : [];
+                                if (is_array($v)) {
+                                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>(array_merge($v, $iext)));
+                                } else {
+                                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>([<?php echo $propertyTypeClassName; ?>::FIELD_VALUE => $v] + $iext));
+                                }
                             }
                         }
+                    } else<?php endif; ?>if (is_array($value)) {
+                        $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>(array_merge($ext, $value)));
+                    } else {
+                        $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>([<?php echo $propertyTypeClassName; ?>::FIELD_VALUE => $value] + $ext));
                     }
-                } else<?php endif; ?>if (is_array($value)) {
-                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>(array_merge($ext, $value)));
-                } else {
-                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>([<?php echo $propertyTypeClassName; ?>::FIELD_VALUE => $value] + $ext));
-                }
-            } elseif ([] !== $ext) {
+                } elseif ([] !== $ext) {
 <?php if ($property->isCollection()) : ?>
-                foreach($ext as $iext) {
-                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($iext));
-                }
+                    foreach($ext as $iext) {
+                        $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($iext));
+                    }
 <?php else : ?>
-                $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($ext));
+                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>($ext));
 <?php endif; ?>
-            } else {
-                $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>(null));
-            }
-        }
-<?php
+                } else {
+                    $this-><?php echo $setter; ?>(new <?php echo $propertyTypeClassName; ?>(null));
+                }
+                $_parsed[self::<?php echo $propertyFieldConst; ?>] = true;
+            }<?php
 return ob_get_clean(); ?>
diff --git a/template/types/methods/constructors/resource_container_property_setter_call.php b/template/types/methods/constructors/resource_container_property_setter_call.php
index e59d9c99..f0b92387 100644
--- a/template/types/methods/constructors/resource_container_property_setter_call.php
+++ b/template/types/methods/constructors/resource_container_property_setter_call.php
@@ -18,6 +18,7 @@
 
 /** @var \DCarbone\PHPFHIR\Definition\Type $type */
 /** @var \DCarbone\PHPFHIR\Definition\Property $property */
+/** @var int $propertyIndex */
 
 $typeClassName = $type->getClassName();
 $propertyName = $property->getName();
@@ -25,51 +26,51 @@
 $propertyType = $property->getValueFHIRType();
 $setter = ($property->isCollection() ? 'add' : 'set') . ucfirst($propertyName);
 
-ob_start(); ?>
-        if (isset($data[self::<?php echo $propertyFieldConst; ?>])) {
+ob_start(); 
+if (0 === $propertyIndex) : ?>
+            if <?php else : ?> else if <?php endif; ?>(self::<?php echo $propertyFieldConst; ?> === $field) {
 <?php if ($property->isCollection()) : ?>
-            if (is_array($data[self::<?php echo $propertyFieldConst; ?>])) {
-                if (is_int(key($data[self::<?php echo $propertyFieldConst; ?>]))) {
-                    $this->set<?php echo ucfirst($propertyName); ?>($data[self::<?php echo $propertyFieldConst; ?>]);
-                } else {
-                    $typeClass = PHPFHIRTypeMap::getContainedTypeFromArray($data[self::<?php echo $propertyFieldConst; ?>]);
+                if (is_array($value)) {
+                    if (is_int(key($value))) {
+                        $this->set<?php echo ucfirst($propertyName); ?>($value);
+                    } else {
+                        $typeClass = PHPFHIRTypeMap::getContainedTypeFromArray($value);
+                        if (null === $typeClass) {
+                            throw new \InvalidArgumentException(sprintf(
+                                '<?php echo $typeClassName; ?> - Unable to determine class for field "<?php echo $propertyName; ?>" from value: %s',
+                                json_encode($value)
+                            ));
+                        }
+                        $this-><?php echo $setter; ?>(new $typeClass($value));
+                    }
+                } elseif ($value instanceof <?php echo PHPFHIR_INTERFACE_CONTAINED_TYPE; ?>) {
+                    $this-><?php echo $setter; ?>($value);
+                }
+<?php else : ?>
+                if (is_object($value)) {
+                    if ($value instanceof <?php echo PHPFHIR_INTERFACE_CONTAINED_TYPE; ?>) {
+                        $this-><?php echo $setter; ?>($value);
+                    } else {
+                        throw new \InvalidArgumentException(sprintf(
+                            '<?php echo $typeClassName; ?> - Field "<?php echo $propertyName; ?>" must be an object implementing <?php echo PHPFHIR_INTERFACE_CONTAINED_TYPE; ?>, object of type %s seen',
+                            get_class($value)
+                        ));
+                    }
+                } elseif (is_array($value)) {
+                    $typeClass = PHPFHIRTypeMap::getContainedTypeFromArray($value);
                     if (null === $typeClass) {
                         throw new \InvalidArgumentException(sprintf(
                             '<?php echo $typeClassName; ?> - Unable to determine class for field "<?php echo $propertyName; ?>" from value: %s',
-                            json_encode($data[self::<?php echo $propertyFieldConst; ?>])
+                            json_encode($value)
                         ));
                     }
-                    $this-><?php echo $setter; ?>(new $typeClass($data[self::<?php echo $propertyFieldConst; ?>]));
-                }
-            } elseif ($data[self::<?php echo $propertyFieldConst; ?>] instanceof <?php echo PHPFHIR_INTERFACE_CONTAINED_TYPE; ?>) {
-                $this-><?php echo $setter; ?>($data[self::<?php echo $propertyFieldConst; ?>]);
-            }
-<?php else : ?>
-            if (is_object($data[self::<?php echo $propertyFieldConst; ?>])) {
-                if ($data[self::<?php echo $propertyFieldConst; ?>] instanceof <?php echo PHPFHIR_INTERFACE_CONTAINED_TYPE; ?>) {
-                    $this-><?php echo $setter; ?>($data[self::<?php echo $propertyFieldConst; ?>]);
+                    $this-><?php echo $setter; ?>(new $typeClass($value));
                 } else {
-                    throw new \InvalidArgumentException(sprintf(
-                        '<?php echo $typeClassName; ?> - Field "<?php echo $propertyName; ?>" must be an object implementing <?php echo PHPFHIR_INTERFACE_CONTAINED_TYPE; ?>, object of type %s seen',
-                        get_class($data[self::<?php echo $propertyFieldConst; ?>])
-                    ));
-                }
-            } elseif (is_array($data[self::<?php echo $propertyFieldConst; ?>])) {
-                $typeClass = PHPFHIRTypeMap::getContainedTypeFromArray($data[self::<?php echo $propertyFieldConst; ?>]);
-                if (null === $typeClass) {
                     throw new \InvalidArgumentException(sprintf(
                         '<?php echo $typeClassName; ?> - Unable to determine class for field "<?php echo $propertyName; ?>" from value: %s',
-                        json_encode($data[self::<?php echo $propertyFieldConst; ?>])
+                        json_encode($value)
                     ));
                 }
-                $this-><?php echo $setter; ?>(new $typeClass($data[self::<?php echo $propertyFieldConst; ?>]));
-            } else {
-                throw new \InvalidArgumentException(sprintf(
-                    '<?php echo $typeClassName; ?> - Unable to determine class for field "<?php echo $propertyName; ?>" from value: %s',
-                    json_encode($data[self::<?php echo $propertyFieldConst; ?>])
-                ));
-            }
 <?php endif; ?>
-        }
-<?php
+            }<?php
 return ob_get_clean();