In a peer-to-peer (P2P) overlay network, a large number and various types of peers are cooperating by exchanging multimedia contents. Here, multimedia streaming is a key technology to realize multimedia applications. A multimedia content is distributed to multiple peers and these peers named contents peers can support other leaf peers with the content. Multimedia contents are required to be efficiently delivered to processes in a real-time manner. Some contents peer may not send packets at a required rate and a communication channel may not support enough Quality of Service (QoS). In this paper, we newly discuss a heterogeneous asynchronous multi-source streaming (HAMS) model where multiple contents peers in parallel transmit packets of a multimedia content to a requesting leaf peer to realize highly reliability and scalability.