Super-peer networks have been proposed to address the issue of search latency and scalability in traditional peer-to-peer (P2P) networks. In a super-peer network, instead of having a fully distributed systems of peer nodes with similar or comparable capabilities, some nodes that possess considerable computing power and resources are designated as super-peers. Each super-peer acts as a server for multiple client peers under it. This hierarchical structure of a super-peer network improves the performance of a super-peer network over traditional P2P networks by handling most search queries between the few super-peer nodes, thereby reducing overall network traffic and improving search latency. In this paper, we address the problem of mutual selection by super-peers and client peers. In particular, we evaluate alternative decision functions used by super-peers to allow new client peers to join the cluster of clients under it. We experiment with peers with known resources and demands. By formally representing and reasoning with capability and query distributions, we develop peer-selection functions that either promote concentration or diversification of capabilities within a cluster. We evaluate the effectiveness of these different selection functions for different environments where peer capabilities are aligned or are independent of their queries. We offer insight and analysis on the effects on inter and intra-peer bandwidth consumption which will allow a super-peer to adopt appropriate peer-selection functions given their expectations about the environment.