Agent interaction in realistic applications is subject to many forms of uncertainty - including information and network uncertainty, trust of and conflicts with other participants, lack of stability in a deal and risks about agreements and commitments. However, one of the most common forms of uncertainty occurs when a group has divergent beliefs about the interaction they are engaged in -- some agents believe an agreement has been reached, while others believe it has been rejected or that they are still bargaining. Such misunderstandings can arise because of loss of network performance, spurious connections, message loss or delays. Against this background, this paper develops synchronisation protocols for a group of agents to attain the same beliefs about an interaction, independent of the reliability of the underlying communication layer. This paper includes and proves theorems about a group's mutual beliefs, on which the safety of an interaction relies. Specifically, protocols for message exchange and belief revision and the reasoning for reachability of states during interactions are presented. Each protocol is proved to show that an increasing level of mutual and consistent belief is reached, thereby guaranteeing an interaction's integrity.