Internal + external custom section

Serverless Framework
1

Inside my serverless.yml I have an external custom section:

custom: ${file(../../serverless.common.yml):custom}

Is it possible to add local custom settings as well?
Something like this:

custom:
  - ${file(../../serverless.common.yml):custom}
  - dotenv:
      path: ../../.env
2

What happens when you try? Remember, you can serverless print to see what the serverless.yml would look like with all variables added and files inserted.