Storing conversations is introducing a massive security hole. One single person in a group can compromise every message from every user.

Secure messages shouldn’t persist and if they do they aren’t secure. Being able to export, upload, and restore an entire conversation history is the opposite of secure.

There is no point in using a secure messaging system if your entire conversation history can be downloaded the minute a single person in your group loses physical security on their device. Just use FB Messenger.