diff --git a/packages/lib/client-only/hooks/use-editor-recipients.ts b/packages/lib/client-only/hooks/use-editor-recipients.ts
index b1fce27e0..88a0f1238 100644
--- a/packages/lib/client-only/hooks/use-editor-recipients.ts
+++ b/packages/lib/client-only/hooks/use-editor-recipients.ts
@@ -9,7 +9,8 @@ import type { UseFormReturn } from 'react-hook-form';
 import { useForm } from 'react-hook-form';
 import { z } from 'zod';
 
-import { isCcRecipient, normalizeRecipientSigningOrders, sortRecipientsForSigningOrder } from '../../utils/recipients';
+import { normalizeGroupedSigningOrders } from '../../utils/recipient-groups';
+import { isCcRecipient, sortRecipientsForSigningOrder } from '../../utils/recipients';
 
 const LocalRecipientSchema = z.object({
   formId: z.string().min(1),
@@ -65,6 +66,24 @@ export const ZEditorRecipientsFormSchema = z
         });
       }
     });
+
+    const seenSigningOrders = new Set<number>();
+
+    data.signers.forEach((signer, index) => {
+      if (signer.role === RecipientRole.CC || typeof signer.signingOrder !== 'number') {
+        return;
+      }
+
+      if (seenSigningOrders.has(signer.signingOrder)) {
+        ctx.addIssue({
+          code: z.ZodIssueCode.custom,
+          message: 'CSC envelopes do not support recipient signing groups.',
+          path: ['signers', index, 'signingOrder'],
+        });
+      }
+
+      seenSigningOrders.add(signer.signingOrder);
+    });
   });
 
 export type TEditorRecipientsFormSchema = z.infer<typeof ZEditorRecipientsFormSchema>;
@@ -101,7 +120,7 @@ export const useEditorRecipients = ({ envelope }: EditorRecipientsProps): UseEdi
 
     const signers: TLocalRecipient[] =
       formRecipients.length > 0
-        ? normalizeRecipientSigningOrders(sortRecipientsForSigningOrder(formRecipients))
+        ? normalizeGroupedSigningOrders(sortRecipientsForSigningOrder(formRecipients))
         : [
             {
               formId: initialId,
diff --git a/packages/lib/utils/recipients.ts b/packages/lib/utils/recipients.ts
index a82a1e251..505389f4b 100644
--- a/packages/lib/utils/recipients.ts
+++ b/packages/lib/utils/recipients.ts
@@ -1,9 +1,10 @@
 import { isSignatureFieldType } from '@documenso/prisma/guards/is-signature-field';
 import type { Envelope, Field, Recipient } from '@prisma/client';
-import { RecipientRole, SigningStatus } from '@prisma/client';
+import { EnvelopeType, RecipientRole, SigningStatus } from '@prisma/client';
 
 import { NEXT_PUBLIC_WEBAPP_URL } from '../constants/app';
 import { AppError, AppErrorCode } from '../errors/app-error';
+import type { TEditorEnvelope } from '../types/envelope-editor';
 import type { TRecipientLite } from '../types/recipient';
 import { extractLegacyIds } from '../universal/id';
 import { zEmail } from './zod';
@@ -141,6 +142,32 @@ export const canRecipientBeModified = (
   return true;
 };
 
+/**
+ * Editor-level wrapper around `canRecipientBeModified`.
+ *
+ * Template recipients and unsaved (id-less) recipients can always be modified.
+ */
+export const canEditorRecipientBeModified = (
+  envelope: Pick<TEditorEnvelope, 'type' | 'recipients' | 'fields'>,
+  recipientId?: number,
+) => {
+  if (envelope.type === EnvelopeType.TEMPLATE) {
+    return true;
+  }
+
+  if (recipientId === undefined) {
+    return true;
+  }
+
+  const recipient = envelope.recipients.find((r) => r.id === recipientId);
+
+  if (!recipient) {
+    return false;
+  }
+
+  return canRecipientBeModified(recipient, envelope.fields);
+};
+
 /**
  * Whether a recipient can have their fields modified by the document owner.
  *