Single Milestone in Multiple Projects

Single Milestone in Multiple Projects

Is there a way to link a single Milestone across Multiple Projects?  Example:  I have a milestone created on a specific customer and I have the same milestone created in our company overall project.  When the customer file is updated I would like a link to update the same milestone in the other project.

I have manually Created a combined overall project made up of all the individual milestones in all the other projects.