Master project within a master project

Question

We use Project Server 2013 and Project Professional 2013.

I  would like to insert a master project as a subproject in another master project but this doesn't seem to be possible. I get an error message "a project cannot be inserted into multiple published master projects" when I  try to publish it. 

What are my options?

Answer 1

What reporting etc are you trying to achieve?

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Rod Gill
Author of the one and only Project VBA Book
www.project-systems.co.nz

Answer 2

We have two departments and each one has their own master project with a few subprojects. I'd like to use a single master project containing the two master projects to show me project progress of both departments combined.

I can't see this progress unless I combine the two master projects.