TestComplete allows you to call tests from another project. To be able to do this, first you need to import these tests to your project. You can import tests of different types: keyword tests, scripts, low-level procedures, and so on. You can even create a "library" of tests and then add them to any project.
You can add a test to a project in the same way you add any existing project item file. To add an existing test to your project:
Right-click the project node in the Project Explorer panel and choose Add | Existing Item from the context menu.
Select the file containing the needed test in the Open File dialog.
Adding an existing test does not create a copy of this test, it just adds a reference to the project. The test file remains in the original project. If you change the imported test in the current project, it will be changed in the original project as well. So, all the projects that have references to the test will use the updated test. If the test was changed outside of TestComplete in an external editor, you should reload its contents from the file. To do this, right-click the needed project element in the Project Explorer and select Reload from the context menu.