The enhancement of reliability and performance in next-generation wireless networks represents a pivotal aspect of the user experience. This defines Wi-Fi 8, which is based on the IEEE 802.11 bn Ultra High Reliability (UHR) standard. Consequently, the objective of Wi-Fi 8 is to enhance the quality of the user experience, optimise transmission efficiency and reliability, and ensure the seamless delivery of high-quality data. In this paper, we propose a Multi-Link/Multi-AP Coordination based Joint Transmission (ML/MAP C-JT) method as a means of enabling seamless roaming, which is a key technology of UHR. In order to achieve this, stations (STAs) and access points (APs) utilising the ML/MAP C-JT method employ multi-link devices (MLDs) that are compatible with multi-link operation (MLO). The Multi-AP is capable of supporting multi-link connectivity with different non-AP MLD, and the AP MLDs are responsible for performing the necessary coordination to ensure a seamless handover of the non-AP MLD. Simulation results show that ML/MAP C-JT significantly improves connection reliability, packet success ratio and overall network throughput compared to traditional single-link and multi-AP only approaches. This paper addresses the feasibility and efficiency of JT in ML/MAP structures and provides insights for the design of next-generation wireless networks.