Multihoming will be preferred by end sites in the future IPv6 Internet. One reason for that is pursuing lower cost and higher performance. Since the proposed shim6 is designed to support multihomed sites delivering packets through multipath, we could optimize cost and performance for Concurrent Multipath Transferring in the TCP layer using extended shim6. Thus, we create optimizing algorithms to dynamically distribute TCP traffic among multiple paths through different ISPs. We implement this intermediation in Layer 4.5 within TCP, assuming shim6 would be extended to support multi locator-pairs for transferring. Our simulation experiments show the validation of our methods, and we are going to implement a real-system for deployment.