use custom application in my own application

Question

Hello,

I have created 2 applications in VB2008. Both applications have several items and code the same.
Now I want to create 1 application with the overlapping items and code.
A second and third application must be made for the specific items and code.
At the end there will be 3 applications:
1. Application with shared items and code
2. Specific application 1 which will use the application from option 1
3. Specific application 2 which will use the application from option 1

From every specific application a deployment project must be made which creates a msi file.
If a specific application is installed the application from option 1 must be installed automatically.

How can the above be achieved?

Thanks in advance.