Hello,
Do you know Business Process Management (BPM) concept's? So if you are interested by modeling your scenarios based on business processes, the perfect choice is BPM, because it is a simplified modeling, resulting from engineering, involves actors with the flow of information that they exchange,Do not hesitate to contact me please for more details, I can send you examples, and if you want other form of flow charts, I can do it. I will be glad to offer you my services.
Thank You!