diff --git a/src/Bundle/ChillActivityBundle/Entity/Activity.php b/src/Bundle/ChillActivityBundle/Entity/Activity.php
index 733a6a1bc..e76bf338a 100644
--- a/src/Bundle/ChillActivityBundle/Entity/Activity.php
+++ b/src/Bundle/ChillActivityBundle/Entity/Activity.php
@@ -130,13 +130,13 @@ class Activity implements HasCenterInterface, HasScopeInterface
      * @ORM\ManyToMany(targetEntity="Chill\PersonBundle\Entity\Person")
      * @Groups({"read"})
      */
-    private Collection $persons;
+    private ?Collection $persons = null;
 
     /**
      * @ORM\ManyToMany(targetEntity="Chill\ThirdPartyBundle\Entity\ThirdParty")
      * @Groups({"read"})
      */
-    private Collection $thirdParties;
+    private ?Collection $thirdParties = null;
 
     /**
      * @ORM\ManyToMany(targetEntity="Chill\DocStoreBundle\Entity\StoredObject")
@@ -147,7 +147,7 @@ class Activity implements HasCenterInterface, HasScopeInterface
      * @ORM\ManyToMany(targetEntity="Chill\MainBundle\Entity\User")
      * @Groups({"read"})
      */
-    private Collection $users;
+    private ?Collection $users = null;
 
     /**
      * @ORM\Column(type="boolean", options={"default"=false})
@@ -351,17 +351,18 @@ class Activity implements HasCenterInterface, HasScopeInterface
         return $this->persons;
     }
 
-    public function setPersons(Collection $persons): self
+    public function setPersons(?Collection $persons): self
     {
         $this->persons = $persons;
 
         return $this;
     }
 
-    public function addThirdParty(ThirdParty $thirdParty): self
+    public function addThirdParty(?ThirdParty $thirdParty): self
     {
-        $this->thirdParties[] = $thirdParty;
-
+        if (null !== $thirdParty) {
+           $this->thirdParties[] = $thirdParty;
+        }
         return $this;
     }
 
@@ -375,7 +376,7 @@ class Activity implements HasCenterInterface, HasScopeInterface
         return $this->thirdParties;
     }
 
-    public function setThirdParties(Collection $thirdParties): self
+    public function setThirdParties(?Collection $thirdParties): self
     {
         $this->thirdParties = $thirdParties;
 
@@ -406,10 +407,11 @@ class Activity implements HasCenterInterface, HasScopeInterface
         return $this;
     }
 
-    public function addUser(User $user): self
+    public function addUser(?User $user): self
     {
-        $this->users[] = $user;
-
+        if (null !== $user) {
+            $this->users[] = $user;
+        }
         return $this;
     }
 
@@ -423,7 +425,7 @@ class Activity implements HasCenterInterface, HasScopeInterface
         return $this->users;
     }
 
-    public function setUsers(Collection $users): self
+    public function setUsers(?Collection $users): self
     {
         $this->users = $users;
 
diff --git a/src/Bundle/ChillActivityBundle/Form/ActivityType.php b/src/Bundle/ChillActivityBundle/Form/ActivityType.php
index a04a4a0a9..b8616eb53 100644
--- a/src/Bundle/ChillActivityBundle/Form/ActivityType.php
+++ b/src/Bundle/ChillActivityBundle/Form/ActivityType.php
@@ -164,40 +164,46 @@ class ActivityType extends AbstractType
         }
 
         if ($activityType->isVisible('persons')) {
-            // TODO Faire évoluer le selecteur et la query <=
-            $builder->add('persons', HiddenType::class);
+            $builder->add('persons', HiddenType::class, [
+               //'data_class' => Person::class,
+            ]);
             $builder->get('persons')
-               //->addModelTransformer(new PersonToIdTransformer($this->om));
-            
                ->addModelTransformer(new CallbackTransformer(
-                   function ($personsAsArray) {
-                       dump('personsAsArray', $personsAsArray); //Doctrine\Common\Collections\ArrayCollection
-                       // transform the array to a string
-                       //return implode(',', $personsAsArray);
-                       return $personsAsArray;
+                   function (iterable $personsAsIterable): string {
+                       $personIds = [];
+                       foreach ($personsAsIterable as $value) {
+                          $personIds[] = $value->getId();
+                       }
+                       return implode(',', $personIds);
                    },
-                   function ($personsAsString) {
-                       dump('personsAsString', $personsAsString); //"1188,1259,1229,1223"
-                       // transform the string back to an array
-                       return explode(',', $personsAsString);
+                   function (?string $personsAsString): array {
+                       return array_map(
+                          fn(string $id): ?Person => $this->om->getRepository(Person::class)->findOneBy(['id' => (int) $id]),
+                          explode(',', $personsAsString)
+                       );
                    }
                ))
-            ;
+           ;
         }
 
         if ($activityType->isVisible('thirdParties')) {
-            // TODO Faire évoluer le selecteur et la query <=
-            $builder->add('thirdParties', HiddenType::class, []);
+            $builder->add('thirdParties', HiddenType::class, [
+               //'data_class' => ThirdParty::class,
+            ]);
             $builder->get('thirdParties')
                ->addModelTransformer(new CallbackTransformer(
-                   function ($personsAsArray) {
-                       // transform the array to a string
-                       //return implode(',', $personsAsArray);
-                       return $personsAsArray;
+                   function (iterable $thirdpartyAsIterable): string {
+                       $thirdpartyIds = [];
+                       foreach ($thirdpartyAsIterable as $value) {
+                          $thirdpartyIds[] = $value->getId();
+                       }
+                       return implode(',', $thirdpartyIds);
                    },
-                   function ($personsAsString) {
-                       // transform the string back to an array
-                       return explode(',', $personsAsString);
+                   function (?string $thirdpartyAsString): array {
+                       return array_map(
+                           fn(string $id): ?ThirdParty => $this->om->getRepository(ThirdParty::class)->findOneBy(['id' => (int) $id]),
+                           explode(',', $thirdpartyAsString)
+                       );
                    }
                ))
            ;
@@ -213,18 +219,23 @@ class ActivityType extends AbstractType
         }
 
         if ($activityType->isVisible('users')) {
-            // TODO Faire évoluer le selecteur et la query <=
-            $builder->add('users', HiddenType::class, []);
+            $builder->add('users', HiddenType::class, [
+               //'data_class' => User::class,
+            ]);
             $builder->get('users')
                ->addModelTransformer(new CallbackTransformer(
-                   function ($personsAsArray) {
-                       // transform the array to a string
-                       //return implode(',', $personsAsArray);
-                       return $personsAsArray;
+                   function (iterable $usersAsIterable): string {
+                       $userIds = [];
+                       foreach ($usersAsIterable as $value) {
+                           $userIds[] = $value->getId();
+                       }
+                       return implode(',', $userIds);
                    },
-                   function ($personsAsString) {
-                       // transform the string back to an array
-                       return explode(',', $personsAsString);
+                   function (?string $usersAsString): array {
+                       return array_map(
+                           fn(string $id): ?User => $this->om->getRepository(User::class)->findOneBy(['id' => (int) $id]),
+                           explode(',', $usersAsString)
+                       );
                    }
                ))
            ;
@@ -298,7 +309,7 @@ class ActivityType extends AbstractType
     public function configureOptions(OptionsResolver $resolver): void
     {
         $resolver->setDefaults([
-            'data_class' => 'Chill\ActivityBundle\Entity\Activity'
+            'data_class' => Activity::class
         ]);
 
         $resolver