diff --git a/packages/app-builder/src/models/scenario-iteration-rule.ts b/packages/app-builder/src/models/scenario-iteration-rule.ts
index b0e62ca94..5c7565744 100644
--- a/packages/app-builder/src/models/scenario-iteration-rule.ts
+++ b/packages/app-builder/src/models/scenario-iteration-rule.ts
@@ -12,7 +12,7 @@ export interface ScenarioIterationRule {
   displayOrder: number;
   name: string;
   description: string;
-  ruleGroup: string | null;
+  ruleGroup: string;
   formula: AstNode | null;
   scoreModifier: number;
   createdAt: string;
@@ -27,7 +27,7 @@ export function adaptScenarioIterationRule(
     displayOrder: dto.displayOrder,
     name: dto.name,
     description: dto.description,
-    ruleGroup: null,
+    ruleGroup: dto.rule_group,
     formula: dto.formula_ast_expression
       ? adaptAstNode(dto.formula_ast_expression)
       : null,
@@ -41,6 +41,7 @@ export interface CreateScenarioIterationRuleInput {
   displayOrder: number;
   name: string;
   description: string;
+  ruleGroup: string;
   formula: AstNode | null;
   scoreModifier: number;
 }
@@ -53,6 +54,7 @@ export function adaptCreateScenarioIterationRuleBodyDto(
     displayOrder: input.displayOrder,
     name: input.name,
     description: input.description,
+    rule_group: input.ruleGroup,
     formula_ast_expression: input.formula ? adaptNodeDto(input.formula) : null,
     scoreModifier: input.scoreModifier,
   };
@@ -63,6 +65,7 @@ export interface UpdateScenarioIterationRuleInput {
   displayOrder?: number;
   name?: string;
   description?: string;
+  ruleGroup?: string;
   formula?: AstNode | null;
   scoreModifier?: number;
 }
@@ -74,6 +77,7 @@ export function adaptUpdateScenarioIterationRuleBodyDto(
     displayOrder: input.displayOrder,
     name: input.name,
     description: input.description,
+    rule_group: input.ruleGroup,
     formula_ast_expression: input.formula
       ? adaptNodeDto(input.formula)
       : input.formula,
diff --git a/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/_edit-view+/rules.tsx b/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/_edit-view+/rules.tsx
index c7d46ab0b..9f0c4c8c7 100644
--- a/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/_edit-view+/rules.tsx
+++ b/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/_edit-view+/rules.tsx
@@ -59,7 +59,7 @@ export async function loader({ request, params }: LoaderFunctionArgs) {
   const ruleGroups = R.pipe(
     rules,
     R.map((rule) => rule.ruleGroup),
-    R.filter(R.isNonNullish),
+    R.filter((val) => !R.isEmpty(val)),
     R.unique(),
   );
 
diff --git a/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/rules.$ruleId.tsx b/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/rules.$ruleId.tsx
index 8a9e96de8..8f3440050 100644
--- a/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/rules.$ruleId.tsx
+++ b/packages/app-builder/src/routes/_builder+/scenarios+/$scenarioId+/i+/$iterationId+/rules.$ruleId.tsx
@@ -109,7 +109,7 @@ export async function loader({ request, params }: LoaderFunctionArgs) {
 const editRuleFormSchema = z.object({
   name: z.string().min(1),
   description: z.string(),
-  ruleGroup: z.string().nullable(),
+  ruleGroup: z.string(),
   scoreModifier: z.coerce.number().int().min(-1000).max(1000),
 });
 type EditRuleFormValues = z.infer<typeof editRuleFormSchema>;
@@ -150,6 +150,7 @@ export async function action({ request, params }: ActionFunctionArgs) {
       formula: astNode,
       name: formValues.name,
       description: formValues.description,
+      ruleGroup: formValues.ruleGroup,
       scoreModifier: formValues.scoreModifier,
     });
 
@@ -539,17 +540,9 @@ function RuleGroup({
   field: ControllerRenderProps<EditRuleFormValues, 'ruleGroup'>;
 }) {
   const { t } = useTranslation(handle.i18n);
-  const value = field.value ?? '';
-  const searchValue = React.useDeferredValue(value);
+  const searchValue = React.useDeferredValue(field.value);
   const ruleGroups = useRuleGroups();
 
-  const onChange = React.useCallback(
-    (value: string) => {
-      field.onChange(value || null);
-    },
-    [field],
-  );
-
   const matches = React.useMemo(
     () => matchSorter(ruleGroups, searchValue),
     [searchValue, ruleGroups],
@@ -558,10 +551,10 @@ function RuleGroup({
   return (
     <ComboboxRoot
       open={ruleGroups.length === 0 ? false : undefined}
-      value={value}
-      setValue={onChange}
-      selectedValue={value}
-      setSelectedValue={onChange}
+      value={field.value}
+      setValue={field.onChange}
+      selectedValue={field.value}
+      setSelectedValue={field.onChange}
     >
       <FormItem className="flex flex-col gap-2">
         <ComboboxLabel render={<FormLabel />}>
diff --git a/packages/app-builder/src/routes/ressources+/scenarios+/$scenarioId+/$iterationId+/rules+/create.tsx b/packages/app-builder/src/routes/ressources+/scenarios+/$scenarioId+/$iterationId+/rules+/create.tsx
index e16259190..60cabf0a3 100644
--- a/packages/app-builder/src/routes/ressources+/scenarios+/$scenarioId+/$iterationId+/rules+/create.tsx
+++ b/packages/app-builder/src/routes/ressources+/scenarios+/$scenarioId+/$iterationId+/rules+/create.tsx
@@ -31,6 +31,7 @@ export async function action({ request, params }: ActionFunctionArgs) {
       formula: null,
       name: t('create_rule.default_name'),
       description: '',
+      ruleGroup: '',
       scoreModifier: 0,
     });
 
diff --git a/packages/app-builder/src/services/editor/current-scenario-iteration.tsx b/packages/app-builder/src/services/editor/current-scenario-iteration.tsx
index 1bc7fb347..5c882977f 100644
--- a/packages/app-builder/src/services/editor/current-scenario-iteration.tsx
+++ b/packages/app-builder/src/services/editor/current-scenario-iteration.tsx
@@ -34,7 +34,7 @@ export const useRuleGroups = () => {
       R.pipe(
         rules,
         R.map((rule) => rule.ruleGroup),
-        R.filter(R.isNonNullish),
+        R.filter((val) => !R.isEmpty(val)),
         R.unique(),
       ),
     [rules],
diff --git a/packages/marble-api/scripts/openapi.yaml b/packages/marble-api/scripts/openapi.yaml
index 197914ed2..d642c8f00 100644
--- a/packages/marble-api/scripts/openapi.yaml
+++ b/packages/marble-api/scripts/openapi.yaml
@@ -4368,15 +4368,6 @@ components:
               type: string
     ScenarioIterationRuleDto:
       type: object
-      required:
-        - id
-        - scenarioIterationId
-        - displayOrder
-        - name
-        - description
-        - formula_ast_expression
-        - scoreModifier
-        - createdAt
       properties:
         id:
           type: string
@@ -4390,6 +4381,8 @@ components:
           type: string
         description:
           type: string
+        rule_group:
+          type: string
         formula_ast_expression:
           nullable: true
           oneOf:
@@ -4399,6 +4392,16 @@ components:
         createdAt:
           type: string
           format: date-time
+      required:
+        - id
+        - scenarioIterationId
+        - displayOrder
+        - name
+        - description
+        - rule_group
+        - formula_ast_expression
+        - scoreModifier
+        - createdAt
     ScenarioValidationDto:
       type: object
       required:
@@ -4452,13 +4455,6 @@ components:
                 $ref: '#/components/schemas/ScenarioValidationErrorDto'
     CreateScenarioIterationRuleBodyDto:
       type: object
-      required:
-        - scenarioIterationId
-        - displayOrder
-        - name
-        - description
-        - formula_ast_expression
-        - scoreModifier
       properties:
         scenarioIterationId:
           type: string
@@ -4469,12 +4465,22 @@ components:
           type: string
         description:
           type: string
+        rule_group:
+          type: string
         formula_ast_expression:
           nullable: true
           oneOf:
             - $ref: '#/components/schemas/NodeDto'
         scoreModifier:
           type: integer
+      required:
+        - scenarioIterationId
+        - displayOrder
+        - name
+        - description
+        - rule_group
+        - formula_ast_expression
+        - scoreModifier
     UpdateScenarioIterationRuleBodyDto:
       type: object
       properties:
@@ -4484,6 +4490,8 @@ components:
           type: string
         description:
           type: string
+        rule_group:
+          type: string
         formula_ast_expression:
           nullable: true
           oneOf:
diff --git a/packages/marble-api/src/generated/marble-api.ts b/packages/marble-api/src/generated/marble-api.ts
index e1ca74a40..340085b2f 100644
--- a/packages/marble-api/src/generated/marble-api.ts
+++ b/packages/marble-api/src/generated/marble-api.ts
@@ -322,6 +322,7 @@ export type CreateScenarioIterationRuleBodyDto = {
     displayOrder: number;
     name: string;
     description: string;
+    rule_group: string;
     formula_ast_expression: (NodeDto) | null;
     scoreModifier: number;
 };
@@ -340,6 +341,7 @@ export type ScenarioIterationRuleDto = {
     displayOrder: number;
     name: string;
     description: string;
+    rule_group: string;
     formula_ast_expression: (NodeDto) | null;
     scoreModifier: number;
     createdAt: string;
@@ -388,6 +390,7 @@ export type UpdateScenarioIterationRuleBodyDto = {
     displayOrder?: number;
     name?: string;
     description?: string;
+    rule_group?: string;
     formula_ast_expression?: (NodeDto) | null;
     scoreModifier?: number;
 };