In the demanding field of practical and feasible quantum cryptography (QC), a multi-party environment is vital for scalable secure communications. This paper presents a four-party quantum key distribution (QKD) simulation framework based on Optical Frequency Division Multiplexing (OFDM) using OptiSystem™. Building upon our prior two-party QKD model, this enhanced framework utilizes wavelength multiplexers and OptiSystem’s subsystem features to streamline transmitter and receiver designs. The implementation includes a centralized server coordinating signal multiplexing and demultiplexing. We reference real-world fiber-optic QKD studies to evaluate expected key generation rates and quantum bit error rates (QBER). The framework supports future research on multi-party authentication and conference key management, offering a modular and replicable simulation for quantum communication development.