If you are still interested in a solution: I found this blog on the Internet (after fooobar.com/questions/390101 / ... ).
You can reveal the functionality inside your add-in by overriding the AddIn.RequestComAddInAutomationService () method and returning the class you want to provide.
In your situation, you can define the class using a method that calls the same code in your add-in as the ribbon button, and provide this VBA method.
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