I have a solution that consists of 3 projects. I've created a deployment project it is only including the dependencies from one of the projects in my solution.
What I've done so far is in my Setup and Deployment project, I right-clicked "Application Folder" to Add --> Project Output. Next I selected my main project from a dropdown and selected "Primary Output". I clicked OK and that project's dependencies were successfully included in the deployment.
I tried to repeat the same process for the other DLLs in my solution, but it didn't include their dependencies.
How do I include all dependencies for each project?
Please note that the dependencies detected by a Visual Studio setup project are more like suggestions. You shouldn't put too much trust in them since false positives are very common.
For a professional installer you should determine the correct dependencies yourself and add them in your project in the appropriate form. For example, some of the dependencies may be part of a runtime or framework which can be added as a prerequisite to your installer.
If you can't figure out what dependencies your application has, you can try using a dependency walker.