Hi,
You can use the OpenSTAAD functions to create a macro in C#.net to link in-house or third-party applications with STAAD.Pro. For more information about OpenSTAAD functions, go to Help > Contents > OpenSTAAD Documentation.
You can go through the following posts. The codes are in VBA, might be helpful for you to understand the work process of the OpenSTAAD functions.
You can also create a service request using the service ticket manager located at www.bentley.com/serviceticketmanager.