Multiparty communication and proactive communication have each been studied extensively, but separately. A combinatorial approach would be to investigate proactive communication in a multiparty setting, aiming to support effective collaboration by leveraging the benefits of both. In this paper we take a first step along this direction, providing formal definitions for multiparty proactive performatives focusing on subscription performatives. Such performatives result in an increased awareness about teammates? mental states - which can trigger additional helpful behaviors.