The invention provides a system and method for generating and evaluating a request in a protocol from another request formed in another protocol. Therein, the request relates to a change of membership to a group and the group relates a service to a host of the service in a communication network. In particular, the method comprises receiving said request, identifying a target group from said request, identifying an associated host to said target group and generating in another protocol another request containing a reference to said target group and said associated host. The request identifies said group and does not uniquely identify said associated host. The invention provides the ability to block a request from proceeding further if it does not belong to a recognized group.