The Customer: The customer is the person or organization that hires the project manager to complete the project. In this case, the customer is Kopi Shop, which is a coffee shop chain. The role of the customer is to provide direction and feedback to the project manager throughout the project. The customer's interest in the project is to have a new system that will improve the efficiency and productivity of their operations. The project manager should cater to the customer's interest by communicating regularly with them, providing updates on the project's progress, and making sure that the new system meets their needs.

The Project Sponsor: The project sponsor is the person or organization that provides the funding for the project. In this case, the project sponsor is Mr$.$ Tam, who is the owner of Kopi Shop. The role of the project sponsor is to provide the necessary resources for the project to be completed. The project sponsor's interest in the project is to have a new system that will improve the efficiency and productivity of their operations. The project manager should cater to the project sponsor's interest by providing regular updates on the project's progress and making sure that the new system meets their needs.

The End$-$Users: The end$-$users are the people who will use the new system once it is complete. In this case, the end$-$users are the employees at Kopi Shop. The role of the end$-$users is to provide feedback on the new system. The end$-$users' interest in the project is to have a new system that will improve the efficiency and productivity of their operations. The project manager should cater to the end$-$users' interest by providing them with training on the new system, making sure that they are comfortable using it$,$ and making sure that they are able to provide feedback on how to improve it$.$ Final answer: In conclusion, the four key stakeholders in the SMA Project are the customer, the project sponsor, the project team, and the end$-$users. The project manager should cater to the stakeholders' interest by communicating regularly with them, providing updates on the project's progress, and making sure that the new system meets their needs.