batch of improvement from quantin's feedback

web/modules/custom/materio_id/materio_id.module

@@ -61,7 +61,16 @@ function computed_field_field_reference_compute($entity_type_manager, $entity, $
  */
 function materio_id_form_node_materiau_edit_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
   // dsm($form_id);
+  // ksm($form);
   $node = $form_state->getFormObject()->getEntity();
+
+  // lock the family filed if already filled
+  if(isset($form['field_famille']) && $family = $node->field_famille->value){
+    // dsm($family);
+    $form['field_famille']['widget']['#disabled'] = true;
+  }
+  
+  // adding reference to the form title
   $ref = $node->field_reference->value;
   // dsm($ref);
 	if($ref != ''){