In peer-to-peer (P2P) overlay networks, objects are distributed to peers in various ways like downloading. Service supported by an object is modeled to be a set of methods and quality of service (QoS). In addition to discovering a peer holding a target object, it is critical to discuss what peer is allowed to manipulate the target object in what method. In this paper, we take an acquaintance approach to finding and manipulating objects in P2P overlay networks. An acquaintance peer of a peer p is a peer whose service the peer p knows and with which the peer p can directly communicate. If an access request is issued, a peer has to find where a target object exists, how to obtain an access right on the target object, and how to manipulate the target object. In this paper, we discuss ways to obtain results satisfying an access request by the cooperation of acquaintances. Acquaintance peers of a peer p may hold different information on target peers since it takes time to propagate change information of the target peers and peers may be faulty. Here, it is critical to discuss how much a peer can trust each acquaintance. First, we define how much a requesting peer is satisfied for each access request issued to an acquaintance. Then, we define the trustworthiness of an acquaintance peer based on the satisfiability. That is, a peer considers an acquaintance to be more trustworthy if the acquaintance returns more satisfiable replies.