We do not have to update the CNAME records for your entire domain (example: abc.com). We simply need to add new CNAME records for a specific subdomain, (example: s2s.abc.com) This process is akin to creating a new address within your existing property.
Adding these records for the subdomain will not affect your main website or cause any crashes. It's a safe and common practice for directing traffic to specific functionalities within a domain.