diff --git a/vendor/magento/module-negotiable-quote/Controller/Adminhtml/Quote/Update.php b/vendor/magento/module-negotiable-quote/Controller/Adminhtml/Quote/Update.php
index dd31d2ef1a8b..612e213a7eb3 100644
--- a/vendor/magento/module-negotiable-quote/Controller/Adminhtml/Quote/Update.php
+++ b/vendor/magento/module-negotiable-quote/Controller/Adminhtml/Quote/Update.php
@@ -90,6 +90,7 @@ public function execute()
         $discountErrorMessage = '';
         try {
             $this->quoteCurrency->updateQuoteCurrency($quoteId);
+            $this->quoteData['avoid_addresses_cache'] = true;
             $this->quoteUpdater->updateQuote($quoteId, $this->quoteData, false);
         } catch (ItemDiscountLockingException $e) {
             $hasItemLockingDiscountException = true;
diff --git a/vendor/magento/module-negotiable-quote/Helper/Quote.php b/vendor/magento/module-negotiable-quote/Helper/Quote.php
index 6346f748b8bc..1f34193e33f6 100644
--- a/vendor/magento/module-negotiable-quote/Helper/Quote.php
+++ b/vendor/magento/module-negotiable-quote/Helper/Quote.php
@@ -26,6 +26,20 @@
  */
 class Quote extends \Magento\Framework\App\Helper\AbstractHelper
 {
+    public const AVAILABLE_OPTIONS_NAMES = [
+        'super_attribute',
+        'options',
+        'bundle_option',
+        'bundle_option_qty',
+        'custom_giftcard_amount',
+        'giftcard_amount',
+        'giftcard_message',
+        'giftcard_recipient_email',
+        'giftcard_recipient_name',
+        'giftcard_sender_email',
+        'giftcard_sender_name'
+    ];
+
     /**
      * @var CartInterface
      */
@@ -268,20 +282,8 @@ public function getFormattedCartPrice(CartItemInterface $item, $quoteCurrency =
     public function retrieveCustomOptions(CartItemInterface $item, $isString = true)
     {
         $options = [];
-        $optionsNames = [
-            'super_attribute',
-            'options',
-            'bundle_option',
-            'custom_giftcard_amount',
-            'giftcard_amount',
-            'giftcard_message',
-            'giftcard_recipient_email',
-            'giftcard_recipient_name',
-            'giftcard_sender_email',
-            'giftcard_sender_name'
-        ];
         $request = $item->getBuyRequest();
-        foreach ($optionsNames as $option) {
+        foreach (self::AVAILABLE_OPTIONS_NAMES as $option) {
             if ($request->hasData($option) && $request->getData($option)) {
                 $options[$option] = $request->getData($option);
             }
diff --git a/vendor/magento/module-negotiable-quote/Model/NegotiableItem/GetNegotiatedPrice.php b/vendor/magento/module-negotiable-quote/Model/NegotiableItem/GetNegotiatedPrice.php
index f7930f3d3b6c..3035d278125f 100644
--- a/vendor/magento/module-negotiable-quote/Model/NegotiableItem/GetNegotiatedPrice.php
+++ b/vendor/magento/module-negotiable-quote/Model/NegotiableItem/GetNegotiatedPrice.php
@@ -66,7 +66,7 @@ private function getNegotiableItem(CartItemInterface $quoteItem): NegotiableQuot
     {
         $negotiableItem = $quoteItem->getExtensionAttributes()->getNegotiableQuoteItem();
 
-        if ($quoteItem->getParentItemId() &&
+        if ($quoteItem->getParentItem() &&
             $quoteItem->getParentItem()->getProductType() === BundledProductType::TYPE_CODE
         ) {
             $negotiableItem = $quoteItem
diff --git a/vendor/magento/module-negotiable-quote/Model/NegotiableItem/NegotiatedPriceApplier.php b/vendor/magento/module-negotiable-quote/Model/NegotiableItem/NegotiatedPriceApplier.php
new file mode 100644
index 000000000000..f20f14dd45f7
--- /dev/null
+++ b/vendor/magento/module-negotiable-quote/Model/NegotiableItem/NegotiatedPriceApplier.php
@@ -0,0 +1,145 @@
+<?php
+/**
+ * ADOBE CONFIDENTIAL
+ *
+ * Copyright 2026 Adobe
+ * All Rights Reserved.
+ *
+ * NOTICE: All information contained herein is, and remains
+ * the property of Adobe and its suppliers, if any. The intellectual
+ * and technical concepts contained herein are proprietary to Adobe
+ * and its suppliers and are protected by all applicable intellectual
+ * property laws, including trade secret and copyright laws.
+ * Dissemination of this information or reproduction of this material
+ * is strictly forbidden unless prior written permission is obtained
+ * from Adobe.
+ */
+declare(strict_types=1);
+
+namespace Magento\NegotiableQuote\Model\NegotiableItem;
+
+use Magento\NegotiableQuote\Api\Data\NegotiableQuoteItemInterface;
+use Magento\NegotiableQuote\Model\QuoteItemHashHandler;
+use Magento\NegotiableQuote\Model\ResourceModel\NegotiableQuoteItem as NegotiableQuoteItemResource;
+use Magento\Quote\Api\Data\CartInterface;
+
+/**
+ * Applies and persists negotiated price data for quote items during quote updates.
+ *
+ * Handles both in-place items (via hash matching from AddNegotiatedPriceInfo) and
+ * reconfigured items that were removed and re-added in memory without a DB save.
+ */
+class NegotiatedPriceApplier
+{
+    /**
+     * @param AddNegotiatedPriceInfo $addNegotiatedPriceInfo
+     * @param QuoteItemHashHandler $quoteItemHashHandler
+     * @param NegotiableQuoteItemResource $negotiableQuoteItemResource
+     */
+    public function __construct(
+        private readonly AddNegotiatedPriceInfo $addNegotiatedPriceInfo,
+        private readonly QuoteItemHashHandler $quoteItemHashHandler,
+        private readonly NegotiableQuoteItemResource $negotiableQuoteItemResource
+    ) {
+    }
+
+    /**
+     * Apply negotiated price data to quote items.
+     *
+     * For reconfigured items (re-added in memory without a DB id), discount data preserved
+     * in $deferredNegotiableData is matched to the new items by product hash before the
+     * standard AddNegotiatedPriceInfo hash-matching runs.
+     *
+     * @param CartInterface $quote
+     * @param array $itemsData items data from the request (may include item_hash entries)
+     * @param array $deferredNegotiableData discount data keyed by productSku
+     * @param array $remainingItems items updated in-place, keyed by item_id
+     */
+    public function apply(
+        CartInterface $quote,
+        array $itemsData,
+        array $deferredNegotiableData = [],
+        array $remainingItems = []
+    ): void {
+        if (!empty($deferredNegotiableData)) {
+            $itemsData = $this->appendReconfiguredItemData(
+                $quote,
+                $itemsData,
+                $deferredNegotiableData,
+                $remainingItems
+            );
+        }
+        $this->addNegotiatedPriceInfo->execute($quote, $itemsData);
+    }
+
+    /**
+     * Persist negotiated price extension attribute data to the negotiable_quote_item table.
+     *
+     * Required when addConfiguredItems internally saves the quote, clearing the CartRepository
+     * identity map. Without this, subsequent reloads in updateQuoteItemsCustomPrices would
+     * lose the in-memory discount data set by AddNegotiatedPriceInfo.
+     *
+     * @param CartInterface $quote
+     */
+    public function persist(CartInterface $quote): void
+    {
+        $itemsToSave = [];
+        foreach ($quote->getAllItems() as $quoteItem) {
+            $negotiableItem = $quoteItem->getExtensionAttributes()?->getNegotiableQuoteItem();
+            if (!$negotiableItem || !$negotiableItem->getItemId()) {
+                continue;
+            }
+            $ext = $negotiableItem->getExtensionAttributes();
+            if (!$ext) {
+                continue;
+            }
+            $negotiableItem->setData(
+                NegotiableQuoteItemInterface::NEGOTIATED_PRICE_TYPE,
+                $ext->getNegotiatedPriceType()
+            );
+            $negotiableItem->setData(
+                NegotiableQuoteItemInterface::NEGOTIATED_PRICE_VALUE,
+                $ext->getNegotiatedPriceValue()
+            );
+            $negotiableItem->setData(
+                NegotiableQuoteItemInterface::IS_DISCOUNTING_LOCKED,
+                (int)$ext->getIsDiscountingLocked()
+            );
+            $itemsToSave[] = $negotiableItem;
+        }
+        if ($itemsToSave) {
+            $this->negotiableQuoteItemResource->saveList($itemsToSave);
+        }
+    }
+
+    /**
+     * Append hash-matched negotiable price entries for items that were reconfigured.
+     *
+     * @param CartInterface $quote
+     * @param array $itemsData
+     * @param array $deferredNegotiableData keyed by productSku
+     * @param array $remainingItems keyed by item_id
+     * @return array
+     */
+    private function appendReconfiguredItemData(
+        CartInterface $quote,
+        array $itemsData,
+        array $deferredNegotiableData,
+        array $remainingItems
+    ): array {
+        foreach ($quote->getAllVisibleItems() as $quoteItem) {
+            if (array_key_exists((int)$quoteItem->getItemId(), $remainingItems)) {
+                continue;
+            }
+            $productSku = $quoteItem->getProduct()->getSku();
+            if (!isset($deferredNegotiableData[$productSku])) {
+                continue;
+            }
+            $entry = $deferredNegotiableData[$productSku];
+            $entry['item_hash'] = $this->quoteItemHashHandler->getItemHashToIdItem($quoteItem);
+            $itemsData[] = $entry;
+            unset($deferredNegotiableData[$productSku]);
+        }
+        return $itemsData;
+    }
+}
diff --git a/vendor/magento/module-negotiable-quote/Model/NegotiableQuoteItemManagement.php b/vendor/magento/module-negotiable-quote/Model/NegotiableQuoteItemManagement.php
index 541b9532d03b..9b83326a6bb9 100644
--- a/vendor/magento/module-negotiable-quote/Model/NegotiableQuoteItemManagement.php
+++ b/vendor/magento/module-negotiable-quote/Model/NegotiableQuoteItemManagement.php
@@ -355,7 +355,7 @@ public function isItemLockedForDiscounting(CartItemInterface $quoteItem): bool
         $this->setNegotiableQuoteItem($quoteItem);
         $negotiableItem = $quoteItem->getExtensionAttributes()->getNegotiableQuoteItem();
 
-        if ($quoteItem->getParentItemId() &&
+        if ($quoteItem->getParentItem() &&
             $quoteItem->getParentItem()->getProductType() === BundledProductType::TYPE_CODE
         ) {
             $negotiableItem = $quoteItem
@@ -434,7 +434,7 @@ private function validateAllItemDiscountLocking(
     private function getNegotiatedPriceData(CartItemInterface $quoteItem): array
     {
         $this->setNegotiableQuoteItem($quoteItem);
-        $quoteItem = ($quoteItem->getParentItemId() &&
+        $quoteItem = ($quoteItem->getParentItem() &&
             $quoteItem->getParentItem()->getProductType() === BundledProductType::TYPE_CODE) ?
         $quoteItem->getParentItem() : $quoteItem;
 
diff --git a/vendor/magento/module-negotiable-quote/Model/QuoteItemsUpdater.php b/vendor/magento/module-negotiable-quote/Model/QuoteItemsUpdater.php
index 8a9941c05459..07291c25985d 100644
--- a/vendor/magento/module-negotiable-quote/Model/QuoteItemsUpdater.php
+++ b/vendor/magento/module-negotiable-quote/Model/QuoteItemsUpdater.php
@@ -20,16 +20,19 @@
 use Magento\Checkout\Model\CartFactory;
 use Magento\Framework\Filter\LocalizedToNormalized;
 use Magento\Framework\Locale\ResolverInterface;
+use Magento\NegotiableQuote\Api\Data\NegotiableQuoteItemInterface;
 use Magento\NegotiableQuote\Helper\Quote;
 use Magento\Quote\Api\Data\CartInterface;
 use Magento\Quote\Api\Data\CartItemInterface;
 use Magento\NegotiableQuote\Model\Quote\TotalsFactory;
-use Magento\NegotiableQuote\Model\NegotiableItem\AddNegotiatedPriceInfo;
+use Magento\NegotiableQuote\Model\NegotiableItem\NegotiatedPriceApplier;
 use Magento\NegotiableQuote\Model\NegotiableItem\AddNegotiatedItemNote;
 use Magento\Framework\Serialize\Serializer\Json;
 
 /**
  * Class for updating quote items attributes and options for complex products.
+ *
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
  */
 class QuoteItemsUpdater
 {
@@ -81,9 +84,9 @@ class QuoteItemsUpdater
      * @param ResolverInterface $resolver
      * @param CartFactory $cartFactory
      * @param TotalsFactory $quoteTotalsFactory
-     * @param AddNegotiatedPriceInfo $addNegotiatedPriceInfo
      * @param AddNegotiatedItemNote $addNegotiatedItemNote
      * @param Json $serializer
+     * @param NegotiatedPriceApplier $negotiatedPriceApplier
      */
     public function __construct(
         \Magento\NegotiableQuote\Helper\Quote $negotiableQuoteHelper,
@@ -91,9 +94,9 @@ public function __construct(
         \Magento\Framework\Locale\ResolverInterface $resolver,
         \Magento\Checkout\Model\CartFactory $cartFactory,
         TotalsFactory $quoteTotalsFactory,
-        private readonly AddNegotiatedPriceInfo $addNegotiatedPriceInfo,
         private readonly AddNegotiatedItemNote $addNegotiatedItemNote,
-        private readonly Json $serializer
+        private readonly Json $serializer,
+        private readonly NegotiatedPriceApplier $negotiatedPriceApplier
     ) {
         $this->negotiableQuoteHelper = $negotiableQuoteHelper;
         $this->cart = $cart;
@@ -116,6 +119,7 @@ public function updateItemsForQuote(\Magento\Quote\Api\Data\CartInterface $quote
         $itemsForAdd = $this->getDataFromArray($itemsData, 'addItems');
         $itemsForUpdate = $this->getDataFromArray($itemsData, 'items');
         $configuredItemsAdd = $this->getDataFromArray($itemsData, 'configuredItems');
+        $deferredNegotiableData = [];
 
         $this->quote->setIsSuperMode(true);
         foreach ($itemsForUpdate as $data) {
@@ -134,6 +138,14 @@ public function updateItemsForQuote(\Magento\Quote\Api\Data\CartInterface $quote
                     parse_str(urldecode($data['config']), $config);
                     $item['config'] = $config;
                     $configuredItemsAdd[] = $item;
+
+                    if (isset($data['negotiated_price_type'])) {
+                        $deferredNegotiableData[$data['productSku']] = [
+                            NegotiableQuoteItemInterface::NEGOTIATED_PRICE_TYPE => $data['negotiated_price_type'],
+                            NegotiableQuoteItemInterface::NEGOTIATED_PRICE_VALUE => $data['negotiated_price_value'],
+                            NegotiableQuoteItemInterface::IS_DISCOUNTING_LOCKED => $data['is_discounting_locked'],
+                        ];
+                    }
                 } else {
                     $itemsForAdd[] = $item;
                 }
@@ -141,12 +153,23 @@ public function updateItemsForQuote(\Magento\Quote\Api\Data\CartInterface $quote
         }
 
         $this->removeQuoteItemsNotInArray($items);
+        $hasConfiguredItems = !empty($configuredItemsAdd);
         $this->addConfiguredItems($configuredItemsAdd);
         $this->addItems($itemsForAdd);
         $this->quote->setIsSuperMode(false);
         $this->addRemovedSkus($quote, $itemsForUpdate);
         $this->addNegotiatedItemNote->execute($this->quote, $this->getDataFromArray($itemsData, 'items'));
-        $this->addNegotiatedPriceInfo->execute($this->quote, $this->getDataFromArray($itemsData, 'items'));
+        $this->negotiatedPriceApplier->apply(
+            $this->quote,
+            $this->getDataFromArray($itemsData, 'items'),
+            $deferredNegotiableData,
+            $items
+        );
+
+        if ($hasConfiguredItems) {
+            $this->negotiatedPriceApplier->persist($this->quote);
+        }
+
         return $this->hasChanges;
     }
 
@@ -221,10 +244,32 @@ private function isNeedReconfigurationItem(CartItemInterface $item, array $data)
         $newConfig = [];
         // phpcs:ignore Magento2.Functions.DiscouragedFunction
         parse_str(urldecode($data['config']), $newConfig);
+        $newConfig = $this->sanitizeConfig($newConfig);
 
         return is_array($oldConfig) && is_array($newConfig) && $oldConfig != $newConfig;
     }
 
+    /**
+     * Filter config
+     *
+     * @param array $config
+     * @return array
+     */
+    private function sanitizeConfig(array $config) : array
+    {
+        $configKeys = array_keys($config);
+        $result = $config;
+        if (in_array('bundle_option', $configKeys)) {
+            $result = [];
+            foreach ($config as $key => $value) {
+                if (in_array($key, $this->negotiableQuoteHelper::AVAILABLE_OPTIONS_NAMES)) {
+                    $result[$key] = $value;
+                }
+            }
+        }
+        return $result;
+    }
+
     /**
      * Remove quote items from quote.
      *
diff --git a/vendor/magento/module-negotiable-quote/Model/QuoteUpdater.php b/vendor/magento/module-negotiable-quote/Model/QuoteUpdater.php
index a303c41d73fa..d8de45b1e97d 100644
--- a/vendor/magento/module-negotiable-quote/Model/QuoteUpdater.php
+++ b/vendor/magento/module-negotiable-quote/Model/QuoteUpdater.php
@@ -131,8 +131,12 @@ public function __construct(
      * @return bool
      * @throws \Magento\Framework\Exception\NoSuchEntityException
      */
-    public function updateQuote($quoteId, array $data, $needLogChanges = true, $needSave = false)
-    {
+    public function updateQuote(
+        $quoteId,
+        array $data,
+        $needLogChanges = true,
+        $needSave = false
+    ) {
         $this->quote = $this->getQuote($quoteId);
         $this->hasChanges = false;
 
@@ -156,10 +160,14 @@ public function updateQuote($quoteId, array $data, $needLogChanges = true, $need
         }
 
         if ($this->hasChanges || $this->needRecalculate) {
+            if (!empty($data['avoid_addresses_cache'])) {
+                $this->quote->setData('avoid_addresses_cache', true);
+            }
             $this->updatePriceQuote($needSave);
             $this->quote->setTotalsCollectedFlag(false);
             $this->quote->collectTotals();
             $this->ruleChecker->checkIsDiscountRemoved($this->quote, $oldRuleIds, $needLogChanges);
+            $this->quote->setData('avoid_addresses_cache', false);
             $priceChange = $this->priceChecker
                 ->setIsProductPriceChanged($this->quote, $oldPriceData, $needLogChanges);
             $this->priceChecker->setIsCartPriceChanged($this->quote, $oldCartPriceData, $needLogChanges);
diff --git a/vendor/magento/module-negotiable-quote/Plugin/Quote/Model/QuoteAddressesCollectionPlugin.php b/vendor/magento/module-negotiable-quote/Plugin/Quote/Model/QuoteAddressesCollectionPlugin.php
new file mode 100644
index 000000000000..3355e092bc80
--- /dev/null
+++ b/vendor/magento/module-negotiable-quote/Plugin/Quote/Model/QuoteAddressesCollectionPlugin.php
@@ -0,0 +1,61 @@
+<?php
+/**
+ * ADOBE CONFIDENTIAL
+ *
+ * Copyright 2025 Adobe
+ * All Rights Reserved.
+ *
+ * NOTICE: All information contained herein is, and remains
+ * the property of Adobe and its suppliers, if any. The intellectual
+ * and technical concepts contained herein are proprietary to Adobe
+ * and its suppliers and are protected by all applicable intellectual
+ * property laws, including trade secret and copyright laws.
+ * Dissemination of this information or reproduction of this material
+ * is strictly forbidden unless prior written permission is obtained
+ * from Adobe.
+ */
+declare(strict_types=1);
+
+namespace Magento\NegotiableQuote\Plugin\Quote\Model;
+
+use Magento\Quote\Model\Quote;
+use Magento\Quote\Model\Quote\AddressFactory;
+use Magento\Quote\Model\ResourceModel\Quote\Address\Collection;
+
+/**
+ * Override addresses collection getter to avoid caching
+ */
+class QuoteAddressesCollectionPlugin
+{
+    /**
+     * @param AddressFactory $addressFactory
+     */
+    public function __construct(
+        private readonly AddressFactory $addressFactory
+    ) {
+    }
+
+    /**
+     * Repopulate addresses collection
+     *
+     * @param Quote $subject
+     * @param Collection|null $result
+     * @return Collection|null
+     */
+    public function afterGetAddressesCollection(
+        Quote $subject,
+        ?Collection $result
+    ) {
+        if ($subject->getExtensionAttributes() && $subject->getExtensionAttributes()->getNegotiableQuote()
+            && $subject->getData('avoid_addresses_cache') === true) {
+            $id = $subject->getId();
+            if ((int)$id !== 0 && !empty($result)) {
+                $result = $this->addressFactory->create()->getCollection()->setQuoteFilter($id);
+            }
+        }
+        foreach ($result as $address) {
+            $address->setQuote($subject);
+        }
+        return $result;
+    }
+}
diff --git a/vendor/magento/module-negotiable-quote/etc/adminhtml/di.xml b/vendor/magento/module-negotiable-quote/etc/adminhtml/di.xml
index 938fd16dee51..263f5e8ee024 100644
--- a/vendor/magento/module-negotiable-quote/etc/adminhtml/di.xml
+++ b/vendor/magento/module-negotiable-quote/etc/adminhtml/di.xml
@@ -20,6 +20,7 @@
         </arguments>
     </type>
     <type name="Magento\Quote\Model\Quote">
+        <plugin name="negotiableQuoteCacheFixer" type="Magento\NegotiableQuote\Plugin\Quote\Model\QuoteAddressesCollectionPlugin"/>
         <plugin name="currencyNegotiableQuoteAdminhtmlPlugin" type="Magento\NegotiableQuote\Plugin\Quote\Model\QuoteAdminhtmlPlugin"/>
     </type>
     <type name="Magento\Catalog\Pricing\Price\TierPrice">