How to: Set Multiple Startup Projects
Visual Studio allows you to specify how more than one project is run when you start the debugger.
To set multiple startup projects
In Solution Explorer, select the solution.
On the Project menu, click Properties. The Solution Property Pages dialog box opens.
Expand the Common Properties node, and click Startup Project.
Click Multiple Startup Projects and set the project actions. For more information, see How to: Modify Project Properties and Configuration Settings.