diff --git a/web/projects/ui/src/app/routes/portal/components/form/form-union/form-union.component.ts b/web/projects/ui/src/app/routes/portal/components/form/form-union/form-union.component.ts
index e426259a6..e8602eeb0 100644
--- a/web/projects/ui/src/app/routes/portal/components/form/form-union/form-union.component.ts
+++ b/web/projects/ui/src/app/routes/portal/components/form/form-union/form-union.component.ts
@@ -30,6 +30,7 @@ export class FormUnionComponent implements OnChanges {
 
   private readonly form = inject(FormGroupName)
   private readonly formService = inject(FormService)
+  private readonly values: Record<string, any> = {}
 
   get union(): string {
     return this.form.value.selection
@@ -37,10 +38,13 @@ export class FormUnionComponent implements OnChanges {
 
   @tuiPure
   onUnion(union: string) {
+    this.values[this.union] = this.form.control.controls['value'].value
     this.form.control.setControl(
       'value',
       this.formService.getFormGroup(
         union ? this.spec.variants[union].spec : {},
+        [],
+        this.values[union],
       ),
       {
         emitEvent: false,
diff --git a/web/projects/ui/src/app/services/form.service.ts b/web/projects/ui/src/app/services/form.service.ts
index 80721380b..453accb8e 100644
--- a/web/projects/ui/src/app/services/form.service.ts
+++ b/web/projects/ui/src/app/services/form.service.ts
@@ -37,18 +37,14 @@ export class FormService {
     }
   }
 
-  getUnionObject(
-    spec: IST.ValueSpecUnion,
-    selected: string | null,
-  ): UntypedFormGroup {
-    const group = this.getFormGroup({
-      selection: this.getUnionSelectSpec(spec, selected),
-    })
+  getUnionObject(spec: IST.ValueSpecUnion, value: any): UntypedFormGroup {
+    const valid = spec.variants[value?.selection]
+    const selected = valid ? value?.selection : spec.default
+    const selection = this.getUnionSelectSpec(spec, selected)
+    const group = this.getFormGroup({ selection })
+    const control = selected ? spec.variants[selected].spec : {}
 
-    group.setControl(
-      'value',
-      this.getFormGroup(selected ? spec.variants[selected].spec : {}),
-    )
+    group.setControl('value', this.getFormGroup(control, [], value?.value))
 
     return group
   }
@@ -134,13 +130,7 @@ export class FormService {
           fileValidators(spec),
         )
       case 'union':
-        const currentSelection = currentValue?.selection
-        const isValid = !!spec.variants[currentSelection]
-
-        return this.getUnionObject(
-          spec,
-          isValid ? currentSelection : spec.default,
-        )
+        return this.getUnionObject(spec, currentValue)
       case 'toggle':
         value = currentValue === undefined ? spec.default : currentValue
         return this.formBuilder.control(value)