diff --git a/sources/Forms/Block/AbstractFormBlock.php b/sources/Forms/Block/AbstractFormBlock.php
index 356b33829..64d91ca30 100644
--- a/sources/Forms/Block/AbstractFormBlock.php
+++ b/sources/Forms/Block/AbstractFormBlock.php
@@ -53,8 +53,11 @@ abstract class AbstractFormBlock
 		$this->InitInputs();
 		$this->InitOutputs();
 		$this->aOptions = array_merge($this->aOptions, $this->InitOptions());
+		$this->BuildForm();
 	}
 
+	abstract protected function BuildForm();
+
 	/**
 	 * Return the form block name.
 	 *
@@ -65,6 +68,17 @@ abstract class AbstractFormBlock
 		return $this->sName;
 	}
 
+	/**
+	 * Return the form block options.
+	 * Options will be passed to FormType for building.
+	 *
+	 * @return array
+	 */
+	public function GetOptions(): array
+	{
+		return $this->aOptions;
+	}
+
 	/**
 	 * Return the form block options.
 	 * Options will be passed to FormType for building.
@@ -183,6 +197,15 @@ abstract class AbstractFormBlock
 		return $this;
 	}
 
+	public function DependsOnParent(string $sInputName, FormBlock $oParentBlock, string $sParentInputName): AbstractFormBlock
+	{
+		$oFormInput = $this->GetInput($sInputName);
+		$oParentFormInput = $oParentBlock->GetInput($sParentInputName);
+		$oFormInput->Bind($oParentFormInput);
+
+		return $this;
+	}
+
 	public function HasConnections(): bool
 	{
 		foreach ($this->aFormInputs as $oFormInput) {
diff --git a/sources/Forms/Block/DataModel/AttributeChoiceFormBlock.php b/sources/Forms/Block/DataModel/AttributeChoiceFormBlock.php
index 69b25b1fc..f1fb82077 100644
--- a/sources/Forms/Block/DataModel/AttributeChoiceFormBlock.php
+++ b/sources/Forms/Block/DataModel/AttributeChoiceFormBlock.php
@@ -44,10 +44,10 @@ class AttributeChoiceFormBlock extends ChoiceFormBlock
 	/** @inheritdoc  */
 	public function UpdateOptions(): array
 	{
-		$aOptions = parent::UpdateOptions();
+		$aOptions = parent::GetOptions();
 
 		$oBinding = $this->GetInput(self::INPUT_CLASS_NAME)->GetBinding();
-		$oConnectionValue = $oBinding->oOutput->Value();
+		$oConnectionValue = $oBinding->oSourceIO->Value();
 
 		$aAttributeCodes = \MetaModel::GetAttributesList($oConnectionValue);
 		$aAttributeCodes = array_combine($aAttributeCodes, $aAttributeCodes) ;
diff --git a/sources/Forms/Block/DataModel/AttributeValueChoiceFormBlock.php b/sources/Forms/Block/DataModel/AttributeValueChoiceFormBlock.php
index 2d7b331ee..13a504ded 100644
--- a/sources/Forms/Block/DataModel/AttributeValueChoiceFormBlock.php
+++ b/sources/Forms/Block/DataModel/AttributeValueChoiceFormBlock.php
@@ -10,7 +10,6 @@ use Combodo\iTop\Forms\Block\Base\ChoiceFormBlock;
 use Combodo\iTop\Forms\Block\IO\Format\AttributeIOFormat;
 use Combodo\iTop\Forms\Block\IO\Format\ClassIOFormat;
 use Combodo\iTop\Forms\Block\IO\FormInput;
-use Combodo\iTop\Forms\FormType\AttributeChoiceType;
 use Combodo\iTop\Forms\FormType\AttributeValueChoiceType;
 
 /**
@@ -47,17 +46,17 @@ class AttributeValueChoiceFormBlock extends ChoiceFormBlock
 
 	public function UpdateOptions(): array
 	{
-		$aOptions = parent::UpdateOptions();
+		$aOptions = parent::GetOptions();
 
 		$oBindingClassName = $this->GetInput(self::INPUT_CLASS_NAME)->GetBinding();
-		if($oBindingClassName->oOutput->Value() === null || $oBindingClassName->oOutput->Value() == "")
+		if($oBindingClassName->oSourceIO->Value() === null || $oBindingClassName->oSourceIO->Value() == "")
 			return $aOptions;
-		$oClassName = $oBindingClassName->oOutput->Value();
+		$oClassName = $oBindingClassName->oSourceIO->Value();
 
 		$oBindingAttribute = $this->GetInput(self::INPUT_ATTRIBUTE)->GetBinding();
-		if($oBindingAttribute->oOutput->Value() === null || $oBindingAttribute->oOutput->Value() == "")
+		if($oBindingAttribute->oSourceIO->Value() === null || $oBindingAttribute->oSourceIO->Value() == "")
 			return $aOptions;
-		$oAttribute = $oBindingAttribute->oOutput->Value();
+		$oAttribute = $oBindingAttribute->oSourceIO->Value();
 
 		$oAttDef = \MetaModel::GetAttributeDef(strval($oClassName), strval($oAttribute));
 		$aValues = $oAttDef->GetAllowedValues();
diff --git a/sources/Forms/Block/FormBlock.php b/sources/Forms/Block/FormBlock.php
index 06f1c01d4..bae93e3ca 100644
--- a/sources/Forms/Block/FormBlock.php
+++ b/sources/Forms/Block/FormBlock.php
@@ -39,4 +39,8 @@ class FormBlock extends AbstractFormBlock
 	{
 		return [];
 	}
+
+	protected function BuildForm(): void
+	{
+	}
 }
\ No newline at end of file
diff --git a/sources/Forms/Block/IO/AbstractFormIO.php b/sources/Forms/Block/IO/AbstractFormIO.php
index b01bf3792..9c9df4760 100644
--- a/sources/Forms/Block/IO/AbstractFormIO.php
+++ b/sources/Forms/Block/IO/AbstractFormIO.php
@@ -12,10 +12,33 @@ class AbstractFormIO
 {
 
 	private AbstractFormBlock $oOwnerBlock;
+	private string $sName;
+	private string $sType;
 
-	public function SetOwnerBlock(AbstractFormBlock $oOwnerBlock): void
+	public function __construct(string $sName, string $sType)
 	{
-		$this->oOwnerBlock = $oOwnerBlock;
+		$this->sName = $sName;
+		$this->sType = $sType;
+	}
+
+	public function GetName(): string
+	{
+		return $this->sName;
+	}
+
+	public function SetName(string $sName): void
+	{
+		$this->sName = $sName;
+	}
+
+	public function GetType(): string
+	{
+		return $this->sType;
+	}
+
+	public function SetType(string $sType): void
+	{
+		$this->sType = $sType;
 	}
 
 	public function GetOwnerBlock(): AbstractFormBlock
@@ -23,4 +46,9 @@ class AbstractFormIO
 		return $this->oOwnerBlock;
 	}
 
+	public function SetOwnerBlock(AbstractFormBlock $oOwnerBlock): void
+	{
+		$this->oOwnerBlock = $oOwnerBlock;
+	}
+
 }
\ No newline at end of file
diff --git a/sources/Forms/Block/IO/FormBinding.php b/sources/Forms/Block/IO/FormBinding.php
index e8f45378b..a76773126 100644
--- a/sources/Forms/Block/IO/FormBinding.php
+++ b/sources/Forms/Block/IO/FormBinding.php
@@ -9,7 +9,7 @@ namespace Combodo\iTop\Forms\Block\IO;
 
 class FormBinding
 {
-	public function __construct(public readonly FormInput $oInput, public readonly FormOutput $oOutput)
+	public function __construct(public readonly FormInput $oDestinationIO, public readonly AbstractFormIO $oSourceIO)
 	{
 
 	}
diff --git a/sources/Forms/Block/IO/FormInput.php b/sources/Forms/Block/IO/FormInput.php
index 57b221f61..e1eba33fd 100644
--- a/sources/Forms/Block/IO/FormInput.php
+++ b/sources/Forms/Block/IO/FormInput.php
@@ -10,45 +10,17 @@ use Combodo\iTop\Forms\Block\FormBlockIOException;
 
 class FormInput extends AbstractFormIO
 {
-	private string $sName;
-
-	private string $sType;
 
 	private FormBinding|null $oBinding = null;
 
-	public function __construct(string $sName, string $sType)
-	{
-		$this->sName = $sName;
-		$this->sType = $sType;
-	}
 
-	public function GetName(): string
+	public function Bind(AbstractFormIO $oSourceIO): void
 	{
-		return $this->sName;
-	}
-
-	public function SetName(string $sName): void
-	{
-		$this->sName = $sName;
-	}
-
-	public function GetType(): string
-	{
-		return $this->sType;
-	}
-
-	public function SetType(string $sType): void
-	{
-		$this->sType = $sType;
-	}
-
-	public function Bind(FormOutput $oFormOutput): void
-	{
-		if($this->sType !== $oFormOutput->GetType()){
-			throw new FormBlockIOException('Cannot connect input types incompatibles ' . $this->sName . ' to ' . $sOutputBlock->GetName() . ' ' . $sOutputName);
+		if($this->GetType() !== $oSourceIO->GetType()){
+			throw new FormBlockIOException('Cannot connect input types incompatibles ' . $this->GetName() . ' from ' . $oSourceIO->GetOwnerBlock()->GetName() . ' ' . $oSourceIO->GetName());
 		}
 
-		$this->oBinding = new FormBinding($this, $oFormOutput);
+		$this->oBinding = new FormBinding($this, $oSourceIO);
 	}
 
 	public function GetBinding(): FormBinding
@@ -58,7 +30,7 @@ class FormInput extends AbstractFormIO
 
 	public function IsDataReady(string $sEventType): bool
 	{
-		return $this->oBinding->oOutput->HasValue($sEventType);
+		return $this->oBinding->oSourceIO->HasValue($sEventType);
 	}
 
 	public function IsBound(): bool
diff --git a/sources/Forms/Block/IO/FormOutput.php b/sources/Forms/Block/IO/FormOutput.php
index 5e4adf3e9..4b3b9f7ef 100644
--- a/sources/Forms/Block/IO/FormOutput.php
+++ b/sources/Forms/Block/IO/FormOutput.php
@@ -11,40 +11,15 @@ use Symfony\Component\Form\FormEvents;
 
 class FormOutput extends AbstractFormIO
 {
-	private string $sName;
-
-	private string $sType;
-
 	private null|AbstractOutputConverter $oConverter;
 	private array $aValues = [];
 
 	public function __construct(string $sName, string $sType, AbstractOutputConverter $oConverter = null)
 	{
-		$this->sName = $sName;
-		$this->sType = $sType;
+		parent::__construct($sName, $sType);
 		$this->oConverter = $oConverter;
 	}
 
-	public function GetName(): string
-	{
-		return $this->sName;
-	}
-
-	public function SetName(string $sName): void
-	{
-		$this->sName = $sName;
-	}
-
-	public function GetType(): string
-	{
-		return $this->sType;
-	}
-
-	public function SetType(string $sType): void
-	{
-		$this->sType = $sType;
-	}
-
 	public function ConvertValue(mixed $oData): mixed
 	{
 		if (is_null($this->oConverter)) {
diff --git a/sources/Forms/FormBuilder/DependencyMap.php b/sources/Forms/FormBuilder/DependencyMap.php
index ad33ec47c..0ad376ad5 100644
--- a/sources/Forms/FormBuilder/DependencyMap.php
+++ b/sources/Forms/FormBuilder/DependencyMap.php
@@ -43,8 +43,8 @@ class DependencyMap
 			foreach ($oDependentBlock->GetInputsBindings() as $sInputName => $oBinding) {
 
 				// connection information
-				$sOutputBlockName = $oBinding->oOutput->GetOwnerBlock()->GetName();
-				$sOutputName = $oBinding->oOutput->GetName();
+				$sOutputBlockName = $oBinding->oSourceIO->GetOwnerBlock()->GetName();
+				$sOutputName = $oBinding->oSourceIO->GetName();
 
 				// initialize map
 				if (!isset($this->aDependenciesMap[$sOutputBlockName])) {