add null price handling

docs/store-operations/pricing/msf-international-enhancements.mdx

@@ -103,11 +103,17 @@ The following fallback behavior applies if you set a product as available for pu
 
   This applies for the prices returned in the [Pricing](/docs/rest-management/pricing/products) endpoint of the REST Management API and the [GraphQL Storefront API](/docs/storefront/graphql). 
 
-  On Stencil storefronts, the product, but not the price, will still be visible. You won't be able to purchase it, but you can still add to wishlist.
+### Update Cornerstone theme
 
-<Callout type="info">
-  You must [update your Stencil theme](https://support.bigcommerce.com/s/article/Marketplace-Theme-Updates) for your Stencil storefront. 
-</Callout>
+If you have an empty price for a product (or variant) in a inclusive or exclusive price list, [update to Cornerstore](https://support.bigcommerce.com/s/article/Marketplace-Theme-Updates) version 6.15 or make adjustments to your current theme to handle `null` prices. You can view the changes required in the [Cornerstone reference PR](https://github.com/bigcommerce/cornerstone/pull/2486/files).
+
+If you update the theme, and you have an empty price, the product, but not the price, will still be visible on the PDP. You won't be able to purchase it, but you can still add to wishlist.
+
+If you do not update the theme, the following will occur:
+- If the variant is the default selection on the PDP, the entire html for the price section will not load. If you change to a variant with a price, the price will still not show.
+- If the variant is not the default selection, the price will load on the PDP without issue. However, when you make the selection to a variant without a price, the price will not change and will display the price of the previously selected variant.
+
+If one of these issues occurs on the theme, and the merchant can not update their theme, entering a price for the product (or variant) causing an issue will resolve the problem. If there is always a price entered for all products on the inclusive or exclusive price list, then no issues will occur. 
 
 ## Additional resources