MsTest Project: How do I include another UnitTest DLL and run all of its tests too?

Question

TLDR: I have a unit test DLL file from another solution. I want to reference that dll and run its tests IN ADDITION TO the tests already in the current project / solution.

We have developed an app suite with three separate applications solutions, plus a shared solution for all of our common objects. All three applications use XML files as their data source. All three use the same schemas of XML, but ultimately each application has nuances to it.

So what we want to do is take our shared solution's unit test project, reference it somehow from the other solutions, then when we run the tests, it not only runs the tests for the current solution, but also executes the tests for the shared DLL.

Thank you for your help!