BigCommerce site: Assign related products to 715 products

We have recently migrated 715 products to our BigCommerce site, www.data-alliance.co. The products were migrated from our current/old version of the website, which is still online and active: www.data-alliance.net. Both the old and the new versions are fully visible on the front-end: On the old version of the site, the related products are visible: www.data-alliance.net. On the new version of the site, [login to view URL]: The products are displaying on the front-end where visitors can see the product's details, but not the related products, yet. We need to have the "Related Products" assigned to the products from the admin panel: This is not a process that can be done by import of a data file, like a CSV file: Rather, this is a manual process: In the CP of [login to view URL], search to find products by SKU and then in the product-editing interface, you click on the "other details" tab, and then uncheck the checkbox that says Find and show related products automatically. Then a list will appear of all product categories (and subcategories nested) and you can, from there, select the related products. We will provide a spreadsheet with the SKU of each product in column A, and the SKUs of the products it is related to, in column B. You can also look up the products on [login to view URL] and see the related products there. You will not have FTP or admin access to [login to view URL], because we are providing the spreadsheet of the related products. When you are finished, the related products of all products on [login to view URL] should match the related products of each of these products on [login to view URL]