Create a Business Group
You can easily manage all of your business listings this way.
Create a group called "Example Company" and add as many locations as you like.
You can also bulk upload to make it easier. Just download all of the businesses you want like so:
When you're adding multiple locations here are some guidelines to follow:
It seems that adding additional locations to an existing GMB listing has been deprecated in favour of individual Business listings with their own location.
I am currently trying to do this myself and the only way I can find is to add a new business under the Businesses' section with the location name forming part of the new business name, otherwise, it'll ...