This is a typical risk of "knowledge concentrated in individuals rather than the enterprise." The fundamental solution is to digitize all customer data, order records, quotation terms, and communication history and centralize them in a system controlled by the enterprise, rather than scattered across personal computers, email, or messaging apps. Specifically, you need to: First, create files with customer basic information, preferred payment methods, order history, and pricing terms that can be accessed by any authorized personnel; Second, maintain version records for every quotation and order sent externally so you can track content changes over time; Third, establish standard operating procedures so that new hires have rules to follow when taking over customer relationships, without having to rebuild from scratch. These practices ensure that your company's customer assets remain within the organization and don't disappear with individual employee departures. Centralizing quotations and orders in a single system and maintaining version records each time they are sent is the concrete means to achieve these outcomes.