I read in this document https://developers.suitecommerce.com/learn-about-our-best-practices-for-suitecommerce-extensions that it is possible to extend an extension by using interfaces and/or adapters. It sounds pretty interesting to me and might help me in optimizing one of our solutions. But I'm currently unknown to these concepts. Do we have any document(s) that might help me understand these?

Thank you Steve. Do we have any examples (implementation) in the SCA source code that I can refer to?

The CMSadapter is how we interface the site's source code with the site management tools

Great. That is helpful, Steve. Thank you!