Customization for Loyalty/reward points - SAGE 200 Evolution

Hi,

One of my client is using Sage 200 Evolution POS system. He wants to add some customisation to the system i.e. adding loyalty rewards for his clients. What he wants is whenever sales invoice gets generated through SAGE system, it should fetch the customer and loyalty point details of the client (through API integration) and allow customer to encash the reward points he/she has in here account. API to fetch the customer and loyalty point detail is already available. Can you pls guide how such customization can be achieved in SAGE 200 Evolution POS system?

Regards,

KC