Seamless handover over heterogeneous mobile environments is a major requirement to the success of the next generation of networks. However, seamless movement requires the control of the quality level and connectivity of communication sessions with no perceived service degradation to the users. This seamless characteristic is equally important for communication sessions encompassing either one or multiple receivers, being the latter called multi-user sessions. This paper presents a solution to allow seamless mobility for multi-user sessions over heterogeneous networks with mobile receivers and static senders. The proposed solution integrates end-to-end Quality of Service (QoS) mapping, QoS adaptation and connectivity control with seamless mobility support. The latter is achieved by using buffers in the mobile nodes and caches in the access-routers together with mobility prediction and context transfer schemes. Simulations present the efficiency of this proposal to setup ongoing sessions and its impact in reducing packet losses and improving the quality of the received video sequence during handover.