A computer implemented method for message data recordation for a sequence of communication events, the computer implemented method comprising: receiving, via a network interface, by a communication processor, an originating message for an initial communication event of the sequence of communication events; parsing, by the communication processor, the originating message for the initial communication event to extract message data for the initial communication event, the extracted message data specifying a first group of participants to which the originating message for the initial communication event is visible; storing, by the communication processor, the extracted message data in a blockchain data structure for the sequence of communication events, the blockchain data structure being replicated by a respective communication processor of each participant of the first group of participants in a respective memory coupled to the respective communication processor; receiving, by the communication processor, a responsive message of a further communication event in the sequence of communication events in response to the originating message, the responsive message comprising responsive message data, the responsive message data comprising permissioning data, the permissioning data specifying a second group of participants to which the responsive message is visible, the second group differing from the first group; creating, by the communication processor, a subsidiary blockchain data structure of the blockchain data structure to support privacy of the responsive message in accordance with the permissioning data; storing, by the communication processor, the responsive message data in the subsidiary blockchain data structure; determining, by the communication processor, whether the sequence of communication events is complete by detecting whether the responsive message data comprises a keyword indicative of completion; if the sequence of communication events is complete, anchoring the subsidiary blockchain data structure to the blockchain data structure; and disseminating a notification of a completion of the sequence of communication events to the first group of participants without disclosing message data stored in the subsidiary blockchain data structure. receiving, via a network interface, by a communication processor, an originating message for an initial communication event of the sequence of communication events; parsing, by the communication processor, the originating message for the initial communication event to extract message data for the initial communication event, the extracted message data specifying a first group of participants to which the originating message for the initial communication event is visible; storing, by the communication processor, the extracted message data in a blockchain data structure for the sequence of communication events, the blockchain data structure being replicated by a respective communication processor of each participant of the first group of participants in a respective memory coupled to the respective communication processor; receiving, by the communication processor, a responsive message of a further communication event in the sequence of communication events in response to the originating message, the responsive message comprising responsive message data, the responsive message data comprising permissioning data, the permissioning data specifying a second group of participants to which the responsive message is visible, the second group differing from the first group; creating, by the communication processor, a subsidiary blockchain data structure of the blockchain data structure to support privacy of the responsive message in accordance with the permissioning data; storing, by the communication processor, the responsive message data in the subsidiary blockchain data structure; determining, by the communication processor, whether the sequence of communication events is complete by detecting whether the responsive message data comprises a keyword indicative of completion; if the sequence of communication events is complete, anchoring the subsidiary blockchain data structure to the blockchain data structure; and disseminating a notification of a completion of the sequence of communication events to the first group of participants without disclosing message data stored in the subsidiary blockchain data structure.