1.Open up the intended master project plan in Project Professional 2007.
2.To add a project select insert> project (and then locate the file). Afterwards save and publish the master project onto Project Server. This will make the subproject a subproject on the server. (Please be aware that you are currently unable to run highlight reports on subprojects).
3.To remove a project plan (and thereby make it a normal project), select the project task from within the master project plan, view task information and then on the advanced tab de-select the check box to “Link to project”. Save and Publish the master project to make the update to project server.
4.Doing this should reinstate your subproject as a normal project – and allow you to run reports on it!!