FitNesse. UserGuide. TestSuites.
CrossReferenceSuites [add child]

Suite Cross References

Sometimes you want to compose a test suite from test pages that are in many different modules, subsystems, or features. For example you might want a test suite that lists all the test pages for the current iteration, or you might want a test suite that lists all the currently passing tests, or you may want to create a test suite for all the quickly executing tests, and another for all the slow tests.

To do this you can use the !see command in a test suite. Any test pages referenced by !see on a suite page will be executed as part of that suite.

The suite page might look like this:

!see .MyProject.MyFeature.IterationOne.StoryOne.TestCaseOne
!see .MyProject.MyFeature.IterationTwo.StoryTwelve.TestCaseThirteen
...