Various kinds of applications like social network service (SNS) are developed and widely used in peer-to-peer (P2P) overlay networks. Here, groups of peers are dynamically and autonomously constructed to achieve some objectives by sharing objects held by the member peers. Each peer holds objects and is assumed to manage its own objects in the role-based access control (RBAC) model in this paper. A role is a collection of access rights, i.e. permissions. A peer defines roles on its own objects and grants and revokes a role to and from another peer. Only a peer granted a role is allowed to make an access to the objects in access rights of the role. In this paper, we discuss how to securely share objects with multiple peers in a society. Each member peer logically views a society to be a collection of society objects and society roles to manipulate the society objects without being conscious of which local peer holds the objects and whether or not the peer is granted access rights. In a society, each member peer plays one or more than one society role. On joining a society, a peer first negotiates with the society an agreement on which roles the peer can support to the society and which society role the peer is granted. In this paper, we discuss how peers do the negotiation with each other to grant and revoke roles in a society.