To configure the RefArch site to use the same customer list as another site, such as RefArchGlobal, the developer should select RefArchGlobal from the dropdown for Customer List in the site settings as shown in the screenshot. This direct selection changes the customer list that the RefArch site references, enabling it to utilize the same customer data as RefArchGlobal without the need for importing customer data or enabling customer list sharing options. This setting is site-specific and directly modified in the site's general settings in Business Manager.