I'm looking for a simple app that can be used to design a conversation with someone. Ideally, I would like it shaped like messenger but where I can fill in the cloud boxes for both parties, or for multiple users for group conversations. After filling out the conversations, I want to be able to share them, with other users, to see how they would have designed a conversation, that could go another way, got example.
The user can also plan trees of how the conversation goes, to follow, in case of different possible interactions one can foresee with one person, and how to follow them.
Inclusion of flow charts and sequence diagrams in the design would be a plus.