I want to invoke Word App from my application, I have also created VSTO application to be hosted inside the word. I want to send starting parameters to the VSTO. I want to show the side pane only if the it was invoked from my other application and automate the document accordingly.
How can i send initial parameters/ arguments to word panel
You can call a public method of your add-in. See Calling Code in Application-Level Add-ins from Other Office Solutions for more information.