diff --git a/src/endpoints/orders.js b/src/endpoints/orders.js
index a3b28cf..f16efec 100644
--- a/src/endpoints/orders.js
+++ b/src/endpoints/orders.js
@@ -29,6 +29,17 @@ class OrdersEndpoint extends BaseExtend {
     )
   }
 
+  UpdateShippingGroup(orderId, shippingGroupId, body) {
+    return this.request.send(
+      `${this.endpoint}/${orderId}/shipping-groups/${shippingGroupId}`,
+      'PUT',
+      {
+        ...body,
+        type: 'shipping_group'
+      }
+    )
+  }
+
   Payment(orderId, body) {
     return this.request.send(`${this.endpoint}/${orderId}/payments`, 'POST', {
       data: body,
diff --git a/src/types/order.d.ts b/src/types/order.d.ts
index 509c1fa..f45bc17 100644
--- a/src/types/order.d.ts
+++ b/src/types/order.d.ts
@@ -135,6 +135,7 @@ export interface ShippingGroupBase extends Identifiable {
       base: FormattedPrice
       tax: FormattedPrice
       fees: FormattedPrice
+      discount?: FormattedPrice
     }
     total_display_price: {
       with_tax: FormattedPrice
@@ -146,10 +147,26 @@ export interface ShippingGroupBase extends Identifiable {
       authorized: FormattedPrice
       without_discount: FormattedPrice
       shipping: FormattedPrice
+      shipping_discount?: FormattedPrice
     }
   }
 }
 
+/**
+ * Fields accepted by PUT /v2/orders/:id/shipping-groups/:id.
+ * `delivery_estimate` is replaced wholesale: omit it and the API clears it.
+ */
+export interface ShippingGroupUpdateBody {
+  address?: OrderShippingAddress
+  shipping_type?: string
+  tracking_reference?: string
+  external_ref?: string
+  delivery_estimate?: {
+    start: string
+    end: string
+  }
+}
+
 
 /**
  * DOCS: https://documentation.elasticpath.com/commerce-cloud/docs/api/orders-and-customers/orders/filtering.html
@@ -587,4 +604,11 @@ export interface OrdersEndpoint
 
   GetShippingGroup(id:string, ShippingGroupId: string): Promise<ResourceIncluded<ShippingGroupBase, ShippingIncluded>>
 
+  /**
+   * Update a Shipping Group on an Order
+   * Description: Updates the address, shipping type, tracking reference, external ref or delivery estimate of a shipping group.
+   * DOCS: https://elasticpath.dev/docs/api/carts/update-order-shipping-group
+   */
+  UpdateShippingGroup(id: string, ShippingGroupId: string, body: ShippingGroupUpdateBody): Promise<Resource<ShippingGroupBase>>
+
 }
diff --git a/test/unit/orders.ts b/test/unit/orders.ts
index e6e067b..7047aca 100644
--- a/test/unit/orders.ts
+++ b/test/unit/orders.ts
@@ -292,6 +292,58 @@ describe('ElasticPath orders', () => {
       })
   })
 
+  it('should update a shipping group on an order', () => {
+    const ElasticPath = ElasticPathGateway({
+      client_id: 'XXX'
+    })
+
+    const address = {
+      first_name: 'John',
+      last_name: 'Doe',
+      line_1: '1 Main Street',
+      city: 'Springfield',
+      postcode: '12345',
+      county: 'Hampden',
+      region: 'MA',
+      country: 'US'
+    }
+
+    // Intercept the API request
+    nock(apiUrl, {
+      reqheaders: {
+        Authorization: 'Bearer a550d8cbd4a4627013452359ab69694cd446615a'
+      }
+    })
+      .put('/orders/order-1/shipping-groups/shipping-group-1', {
+        data: {
+          type: 'shipping_group',
+          address,
+          delivery_estimate: {
+            start: '2026-09-10T00:00:00Z',
+            end: '2026-09-17T00:00:00Z'
+          }
+        }
+      })
+      .reply(200, {
+        data: {
+          id: 'shipping-group-1',
+          type: 'shipping_group',
+          address
+        }
+      })
+
+    return ElasticPath.Orders.UpdateShippingGroup('order-1', 'shipping-group-1', {
+      address,
+      delivery_estimate: {
+        start: '2026-09-10T00:00:00Z',
+        end: '2026-09-17T00:00:00Z'
+      }
+    }).then(response => {
+      assert.propertyVal(response.data, 'id', 'shipping-group-1')
+      assert.propertyVal(response.data.address, 'city', 'Springfield')
+    })
+  })
+
   it('should get orders attributes', () => {
     const ElasticPath = ElasticPathGateway({
       client_id: 'XXX'