How to: Add a Reference to a VSIX Package
If your extension depends on other extensions (dependencies), you can deploy a VSIX package that installs any dependencies that are not already present on the target computer, and then installs your extension. To accomplish this, include the VSIX packages for the dependencies as references in the VSIX package for your extension.
When you double-click source.extension.vsixmanifest in Solution Explorer, the file opens in Manifest Designer. You can then add a reference to an installed extension or to any .vsix file on the computer.
In Manifest Designer, click the Add Reference button.
In the Add VSIX Reference dialog box, click Select Installed Extension and select an extension on the list. Click OK.
Build the solution.
Visual Studio creates a VSIX package that includes the reference.
In Manifest Designer, click the Add Reference button.
In the Add VSIX Reference dialog box, click Add payload to VSIX and then type the path of the .vsix file that contains the extension to be referenced. Click OK.
Build the solution.
Visual Studio creates a VSIX package that includes the reference.
How to: Prepare Extensions for Windows Installer Deployment