A question asked occasionally in the Microsoft Project and Project Online user forums is this: “How can I link a task in one project with a task in another project?” The heart of this question is that the project manager needs to know how to create cross-project dependencies. This question is relevant to almost all Microsoft Project users, regardless of whether you’re managing standalone projects using only the Project desktop client, or whether you’re using Project with a PPM tool, such as Project Server or Project Online.

In fact, I recently answered this exact question for a user in the Project Server forum for administrators. Because the answer to this question requires a “trick,” I thought I would share the answer with you so that you can apply this knowledge in your own project management environment.

Following are the steps to take to create cross-project links between two or more projects:

  1. In Microsoft Project, open each of the projects that you want to link. If you’re using Project Server or Project Online, you must open each of your enterprise projects and check them out for editing in Project (you can’t perform this operation in PWA). If you’re using the Project desktop application only, simply open each of your MPP files in Microsoft Project.
  1. Click the View tab to display the View ribbon shown in Figure 1.

Figure 1: The View ribbon New Window button

  1. In the Window section of the View ribbon, click the New Window button.
  1. In the New Window dialog shown in Figure 2, select each of the open projects, then click the View pick list and select the Gantt Chart view.

Figure 2: The New Window dialog

  1. In the New Window dialog, click OK to create a temporary master project with each of the selected projects inserted as subprojects. Notice in Figure 3 that Project automatically expands tasks in each of the subprojects in the temporary master project.

Figure 3: Temporary master project

  1. In the temporary master project, select a Predecessor task in one project, press and hold the Ctrl key, and then select a Successor task in another project.
  1. In the Schedule section of the Task ribbon, click the Link the Selected Tasks button to link the tasks. This will create a cross-project dependency (also known as a “cross-project link”) between the two projects.
  1. Repeat steps six and seven until you have created all the required cross-project links. For example, notice in Figure 4 that I linked the Design Module A, Design Module B and Design Module C tasks across three projects.

Figure 4: Cross-project links set

Warning: As of the date this is written, because of an unfixed bug in the Microsoft Project 2016 desktop application, the software doesn’t display the link lines for the cross-project dependencies you set.

  1. Click File | Close to close the temporary master project. When prompted in a warning dialog to save the changes, click the No button, as shown in Figure 5.

Figure 5: Warning dialog to save changes to the master project

Your open projects will now contain the cross-project dependencies that you set in the temporary master project. Project will format the external Predecessors and external Successors as “ghost tasks” using gray text and gray Gantt bars, such as for the two external tasks shown in Figure 6.

Figure 6: External tasks set

Remember that the external task dependencies aren’t stored in the master project; they’re stored in the individual subprojects. This is why the master project is temporary — meaning that you don’t need to save the changes when you close it. All you need to do at this point is to save and close each of your open projects to maintain the cross-project dependencies you set.