Creating easy-to-maintain content

My company is planning to build a bunch of Storyline courses that should all have a similar look and feel.  We aim to be as consistent as possible. 

I was thinking that I would create a master project that would have current versions of all the master pages, the corporate color theme, some sample slides, and the correct fonts specified.  Then people can build from that, using the built-in master pages and choosing from theme colors and leaving the fonts alone. 

But then what happens when our branding changes after we have dozens of courses developed and we need to add a new logo and a different backgrounds to all the master pages in all those projects?    I was hoping that it would be possible to drag a master page out of one project and drop it into another project that has a master page with the same name and replace it, but apparently that's not how it works.    

Has anyone been through this and determined the most efficient way to replace all the master pages in umpteen projects with a new version?