A developer customized the Cart-Show controller routewith a LINK cartridge that adds social media data.

Appending the Cart-Show controller route in the client cartridge is the best approach to meet the requirement of adding a datalayer object without affecting the existing LINK cartridge. By appending the controller route, the developer ensures that any modifications are isolated to the client cartridge, which maintains the integrity and functionality of the LINK cartridge. Adding the datalayer object to the viewData variable allows for seamless integration and ensures that the datalayer object is available for use in the view without interfering with the base functionality of the Cart-Show route. This approach allows for easy removal or modification of the LINK cartridge without necessitating changes to the core functionality implemented in the client cartridge.